Apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals

ABSTRACT

A method and an apparatus for transmitting broadcast signals thereof are disclosed. The apparatus for transmitting broadcast signals, the apparatus comprises an encoder for encoding service data corresponding to each of a plurality of data transmission path, wherein each of the data transmission path carries at least one service component, a frame builder for building at least one signal frame included in a super frame, wherein each of signal frames includes the encoded service data and the encoded signaling data, a modulator for modulating the at least one signal frame by an OFDM (Orthogonal Frequency Division Multiplex) scheme, wherein each of the modulated signal frame includes a preamble having basic transmission parameters, wherein a length of the preamble is extendable and a transmitter for transmitting the broadcast signals carrying the at least one modulated signal frame.

BACKGROUND OF THE INVENTION

This application claims the benefit of U.S. Provisional Application Nos.61/925,196, filed on Jan. 8, 2014 and 61/933,304, filed on Jan. 29,2014, which are hereby incorporated by reference as if fully set forthherein.

Field of the Invention

The present invention relates to an apparatus for transmitting broadcastsignals, an apparatus for receiving broadcast signals and methods fortransmitting and receiving broadcast signals.

Discussion of the Related Art

As analog broadcast signal transmission comes to an end, varioustechnologies for transmitting/receiving digital broadcast signals arebeing developed. A digital broadcast signal may include a larger amountof video/audio data than an analog broadcast signal and further includevarious types of additional data in addition to the video/audio data,

That is, a digital broadcast system can provide HI) (high definition)images, multi-channel audio and various additional services. However,data transmission efficiency for transmission of large amounts of data,robustness of transmission/reception networks and network flexibility inconsideration of mobile reception equipment need to be improved fordigital broadcast.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an apparatus fortransmitting broadcast signals and an apparatus for receiving broadcastsignals for future broadcast services and methods for transmitting andreceiving broadcast signals for future broadcast services.

An object of the present invention is to provide an apparatus and methodfor transmitting broadcast signals to multiplex data of a broadcasttransmission/reception system providing two or more different broadcastservices in a time domain and transmit the multiplexed data through thesame RF signal bandwidth and an apparatus and method for receivingbroadcast signals corresponding thereto.

Another object of the present invention is to provide an apparatus fortransmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals toclassify data corresponding to services by components, transmit datacorresponding to each component as a data pipe, receive and process thedata

Still another object of the present invention is to provide an apparatusfor transmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals tosignal signaling information necessary to provide broadcast signals.

Technical Solution

To achieve the object and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod for transmitting broadcast signals, the method comprises encodingservice data corresponding to each of a plurality of data transmissionpath, wherein each of the data transmission path carries at least oneservice component, building at least one signal frame included in asuper-frame, wherein each of signal frames includes the encoded servicedata, modulating the at least one signal frame by an OFDM (OrthogonalFrequency Division Multiplex) scheme, wherein each of the modulatedsignal frame includes a preamble having basic transmission parameters,wherein a length of the preamble is extendable and transmitting thebroadcast signals carrying the at least one modulated signal frame.

Advantageous Effects

The present invention can process data according to servicecharacteristics to control QoS (Quality of Services) for each service orservice component, thereby providing various broadcast services.

The present invention can achieve transmission flexibility bytransmitting various broadcast services through the same RF signalbandwidth.

The present invention can improve data transmission efficiency andincrease robustness of transmission/reception of broadcast signals usinga MIMO system.

According to the present invention, it is possible to provide broadcastsignal transmission and reception methods and apparatus capable ofreceiving digital broadcast signals without error even with mobilereception equipment or in an indoor environment.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiments) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings;

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

FIGS. 2A and 2B illustrate an input formatting block according to oneembodiment of the present invention.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

FIGS. 5A and 5B illustrate a BICM block according to an embodiment ofthe present invention.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

FIG. 8 illustrates an OFDM generation block according to an embodimentof the present invention.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

FIGS. 10A, 10B, 10C, and 10D illustrate a frame structure according toan embodiment of the present invention.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

FIGS. 19A and 19B illustrate FIC mapping according to an embodiment ofthe present invention.

FIGS. 20A and 20B illustrate a type of DP according to an embodiment ofthe present invention.

FIGS. 21A and 21B illustrate DP mapping according to an embodiment ofthe present invention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIGS. 23 A and 23B illustrate a bit interleaving according to anembodiment of the present invention.

FIGS. 24A and 24B illustrate a cell-word demultiplexing according to anembodiment of the present invention.

FIGS. 25A, 25B, and 25C illustrate a time interleaving according to anembodiment of the present invention.

FIGS. 26A and 26B illustrate the basic operation of a twisted row-columnblock interleaver according to an embodiment of the present invention.

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another embodiment of the present invention.

FIG. 28 illustrates a diagonal-wise reading pattern of a twistedrow-column block interleaver according to an embodiment of the presentinvention.

FIG. 29 illustrates interlaved XFECBLOCKs from each interleaving arrayaccording to an embodiment of the present invention.

FIG. 30 illustrates a preamble insertion block according to anembodiment of the present invention.

FIG. 31 illustrates preamble structures according to an embodiment ofthe present invention.

FIG. 32 illustrates a preamble insertion block according to anembodiment of the present invention.

FIG. 33 illustrates a preamble insertion block according to anembodiment of the present invention.

FIG. 34 is a graph showing a scrambling sequence according to anembodiment of the present invention.

FIG. 35 illustrates examples of scrambling sequences modified from thebinary chirp-like sequence according to an embodiment of the presentinvention.

FIG. 36 illustrates preamble signaling according to one embodiment ofthe present invention.

FIG. 37 illustrates a signaling information structure in the preambleaccording to an embodiment of the present invention.

FIG. 38 illustrates a procedure of processing signaling data transmittedthrough the preamble according to an embodiment of the presentinvention.

FIG. 39 illustrates a procedure of processing signaling data transmittedthrough the preamble according to an embodiment of the presentinvention.

FIGS. 40A and 40B show mathematical expressions representingrelationships between input information and output information ormapping rules of the DQPSK/DBPSK mapper 17040 according to an embodimentof the present invention.

FIG. 41 illustrates a differential encoding operation that can beperformed by a preamble insertion module according to an embodiment ofthe present invention.

FIG. 42 illustrates a differential encoding operation that can beperformed by a preamble insertion module according to another embodimentof the present invention.

FIG. 43 is a block diagram of a correlation detector included in apreamble detector according to an embodiment of the present invention.

FIG. 44 illustrates a signaling decoder of a preamble detector accordingto an embodiment of the present invention.

FIG. 45 illustrates a signaling decoder of a preamble detector accordingto an embodiment of the present invention.

FIG. 46 illustrates a signaling decoder of a preamble detector accordingto an embodiment of the present invention.

FIG. 47 is a diagram showing a preamble structure according to anembodiment of the present invention.

FIG. 48 is a block diagram of a preamble insertion block according to anembodiment of the present invention.

FIG. 49 is a detailed block diagram of a correlation detector in apreamble detector according to an embodiment of the present invention.

FIG. 50 is a detailed block diagram of a correlation detector in apreamble detector according to another embodiment of the presentinvention.

FIGS. 51A, 51B, and 51C illustrate a frame structure of a broadcastsystem according to an embodiment of the present invention.

FIGS. 52A, 52B, and 52C illustrate DPs according to an embodiment of thepresent invention.

FIGS. 53A and 53B illustrate type I DPs according to an embodiment ofthe present invention.

FIG. 54 illustrates type. DPs according to an embodiment of the presentinvention.

FIGS. 55A and 55B illustrate type3 DPs according to an embodiment of thepresent invention.

FIGS. 56A and 56B illustrate RBs according to an embodiment of thepresent invention.

FIGS. 57A, 57B, and 57C illustrate a procedure for mapping RBs to framesaccording to an embodiment of the present invention.

FIG. 58 illustrates an RB mapping of type 1 DPs according to anembodiment of the present invention.

FIG. 59 illustrates an RB mapping of type2 DPs according to anembodiment of the present invention.

FIG. 60 illustrates an RB mapping of type3 DPs according to anembodiment of the present invention.

FIGS. 61A and 61B illustrate an RB mapping of type1 DPs according toanother embodiment of the present invention.

FIGS. 62A and 62B illustrate an RB mapping of type 1 DPs according toanother embodiment of the present invention.

FIGS. 63A and 63 B illustrate an RB mapping of type 1 DPs according toanother embodiment of the present invention.

FIGS. 64A and 64B illustrate an RB mapping of type2 DPs according toanother embodiment of the present invention.

FIGS. 65A and 65B illustrate an RB mapping of type2 DPs according toanother embodiment of the present invention.

FIGS. 66A and 66B illustrate an RB mapping of type3 DPs according toanother embodiment of the present invention.

FIG. 67 illustrates an RB mapping of type 3 DPs according to anotherembodiment of the present invention.

FIGS. 68A and 68B illustrate a signaling information according to anembodiment of the present invention.

FIG. 69 illustrates a graph showing the number of bits of a PLSaccording to the number of DPs according to an embodiment of the presentinvention.

FIGS. 70A and 70B illustrate a procedure for demapping DPs according toan embodiment of the present invention.

FIGS. 71A and 71B illustrate signal frame structures according toanother embodiment of the present invention.

FIG. 72 is a diagram showing a frame structure according to anembodiment of the present invention.

FIG. 73 is a diagram showing the structure of OFDM symbols included inone frame.

FIG. 74 is a table showing Signaling format for FRU configuration.

FIG. 75 is a diagram showing preamble signaling of FRU configurationaccording to an embodiment of the present invention.

FIG. 76 is a diagram showing PLS signaling of FRU configurationaccording to an embodiment of the present invention.

FIG. 77 is a diagram showing syntax of the PLS signaling field describedabove in relation to FIG. 76.

FIG. 78 is a table showing Number of OFDM symbols per frame for each FFTand frame length according to an embodiment of the present invention.

FIG. 79 is a table showing frame length in millisecond per frame foreach FFT and GI fraction according to an embodiment of the presentinvention.

FIG. 80 is a table showing Number of OFDM symbols per frame for each FFTand frame length according to an embodiment of the present invention.

FIG. 81 is a flowchart of a broadcast signal transmission methodaccording to an embodiment of the present invention.

FIG. 82 is a flowchart of a broadcast signal reception method accordingto an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will no w be made in detail to the preferred embodiments ofthe present invention, examples of which are illustrated in theaccompanying drawings. The detailed description, which will be givenbelow with reference to the accompanying drawings, is intended toexplain exemplary embodiments of the present invention, rather than toshow the only embodiments that can be implemented according to thepresent invention. The following detailed description includes specificdetails in order to provide a thorough understanding of the presentinvention. However, it will be apparent to those skilled in the art thatthe present invention may be practiced without such specific details.

Although most terms used in the present invention have been selectedfrom general ones widely used in the art, some terms have beenarbitrarily selected by the applicant and their meanings are explainedin detail in the following description as needed. Thus, the presentinvention should be understood based upon the intended meanings of theterms rather than their simple names or meanings.

The present invention provides apparatuses and methods for transmittingand receiving broadcast signals for future broadcast services. Futurebroadcast services according to an embodiment of the present inventioninclude a terrestrial broadcast service, a mobile broadcast service, aUHDTV service, etc. The present invention may process broadcast signalsfor the future broadcast services through non-MIMO (Multiple InputMultiple Output) or MIMO according to one embodiment. A non-MIMO schemeaccording to an embodiment of the present invention may include a MISO(Multiple Input Single Output) scheme, a SISO (Single Input SingleOutput) scheme, etc.

While MISO or MIMO uses two antennas in the following for convenience ofdescription, the present invention is applicable to systems using two ormore antennas.

The present invention may defines three physical layer (PL)profiles—base, handheld and advanced profiles-each optimized to minimizereceiver complexity while attaining the performance required for aparticular use case. The physical layer (PHY) profiles are subsets ofall configurations that a corresponding receiver should implement.

The three PHY profiles share most of the functional blocks but differslightly in specific blocks and/or parameters. Additional PHY profilescan be defined in the future. For the system evolution, future profilescan also be multiplexed with the existing profiles in a single RFchannel through a future extension frame (FEF). The details of each PHYprofile are described below.

1. Base Profile

The base profile represents a main use ease for fixed receiving devicesthat are usually connected to a roof-top antenna. The base profile alsoincludes portable devices that could be transported to a place butbelong to a relatively stationary reception category, Use of the baseprofile could be extended to handheld devices or even vehicular by someimproved implementations, but those use cases are not expected for thebase profile receiver operation.

Target SNR range of reception is from approximately 10 to 20 dB, whichincludes the 15 dB SNR recaption capability of the existing broadcastsystem (e.g. ATSC A/53). The receiver complexity and power consumptionis not as critical as in the battery-operated handheld devices, whichwill use the handheld profile. Key system parameters for the baseprofile are listed in below table 1.

TABLE 1 LDPC codeword length 16K, 64K bits Constellation size 4~10 bpcu(bits per channel use) Time de-interleaving memory size ≤2¹⁹ data cellsPilot patterns Pilot pattern for fixed reception FFT size 16K, 32Kpoints

2. Handheld Profile

The handheld profile is designed for use in handheld and vehiculardevices that operate with battery power. The devices can be moving withpedestrian or vehicle speed. The power consumption as well as thereceiver complexity is very important for the implementation of thedevices of the handheld profile. The target SNR range of the handheldprofile is approximately 0 to 10 dB, but can be configured to reachbelow 0 dB when intended for deeper indoor reception.

In addition to low SNR capability, resilience to the Doppler Effectcaused by receiver mobility is the most important performance attributeof the handheld profile. Key system parameters for the handheld profileare listed in the below table 2.

TABLE 2 LDPC codeword length 16K bits Constellation size 2~8 bpcu Timede-interleaving memory size ≤2¹⁸ data cells Pilot patterns Pilotpatterns for mobile and indoor reception FFT size 8K, 16K points

3. Advanced Profile

The advanced profile provides highest channel capacity at the cost ofmore implementation complexity. This profile requires using MIMOtransmission and reception, and UHDTV service is a target use case forwhich this profile is specifically designed. The increased capacity canalso be used to allow an increased number of services in a givenbandwidth, e.g., multiple SDTV or HDTV services.

The target SNR range of the advanced profile is approximately 20 to 30dB. MIMO transmission may initially use existing elliptically-polarizedtransmission equipment, with extension to full-power cross-polarizedtransmission in the future. Key system parameters for the advancedprofile are listed in below table 3.

TABLE 3 LDPC codeword length 16K bits Constellation size 2~8 bpcu Timede-interleaving memory size ≤2¹⁸ data cells Pilot patterns Pilotpatterns for mobile and indoor reception FFT size 8K, 16K points

In this case, the base profile can be used as a profile for both theterrestrial broadcast service and the mobile broadcast service. That is,the base profile can be used to define a concept of a profile whichincludes the mobile profile. Also, the advanced profile can be dividedadvanced profile for a base profile with MIMO and advanced profile for ahandheld profile with MIMO. Moreover, the three profiles can be changedaccording to intention of the designer.

The following terms and definitions may apply to the present invention.The following terms and definitions can be changed according to design.

auxiliary stream: sequence of cells carrying data of as yet undefinedmodulation and coding, which may be used for future extensions or asrequired by broadcasters or network operators

base data pipe: data pipe that carries service signaling data

baseband frame (or BBFRAME): set of Kbch bits which form the input toone FEC encoding process (BCH and LDPC encoding)

cell: modulation value that is carried by one carrier of the OFDMtransmission

coded block: LDPC-encoded block of PLS1 data or one of the LDPC-encodedblocks of PLS2 data

data pipe: logical channel in the physical layer that carries servicedata or related metadata, which may carry one or multiple service(s) orservice component(s).

data pipe unit: a basic unit for allocating data cells to a DP in aframe.

data symbol: OFDM symbol in a frame which is not a preamble symbol (theframe signaling symbol and frame edge symbol is included in the datasymbol)

DP_ID: this 8 bit field identifies uniquely a DP within the systemidentified by the SYSTEM_ID

dummy cell: cell carrying a pseudo random value used to fill theremaining capacity not used for PLS signaling, DPs or auxiliary streams

emergency alert channel: part of a frame that carries EAS informationdata

frame; physical layer time slot that starts with a preamble and endswith a frame edge symbol

frame repetition unit: a set of frames belonging to same or differentphysical layer profile including a FEF, which is repeated eight times ina super-frame

fast information channel: a logical channel in a frame that carries themapping information between a service and the corresponding base DP

FECBLOCK: set of LDPC-encoded bits of a DP data

FFT size: nominal FFT size used for a particular mode, equal to theactive symbol period Ts expressed in cycles of the elementary period T

frame signaling symbol: OFDM symbol with higher pilot density used atthe start of a frame in certain combinations of FFT size, guard intervaland scattered pilot pattern, which carries a part of the PLS data

frame edge symbol: OFDM symbol with higher pilot density used at the endof a frame in certain combinations of FFT size, guard interval andscattered pilot pattern

frame-group: the set of all the frames having the same PHY profile typein a super-frame.

future extension frame: physical layer time slot within the super-framethat could be used for future extension, which starts with a preamble

Futurecast UTB system: proposed physical layer broadcasting system, ofwhich the input is one or more MPEG2-TS or IP or general stream(s) andof which the output is an RF signal

input stream: A stream of data for an ensemble of services delivered tothe end users by the system.

normal data symbol; data symbol excluding the frame signaling symbol andthe frame edge symbol

PHY profile: subset of all configurations that a corresponding receivershould implement

PLS: physical layer signaling data consisting of PLS1 and PLS2

PLS1 : a first set of PLS data carried in the FSS symbols having a fixedsize, coding and modulation, which carries basic information about thesystem as well as the parameters needed to decode the PLS2

NOTE: PLS1 data remains constant for the duration of a frame-group.

PLS2: a second set of PLS data transmitted in the FSS symbol, whichcarries more detailed PLS data about the system and the DPs

PLS2 dynamic data: PLS2 data that may dynamically change frame-by-frame

PLS2 static data: PLS2 data that remains static for the duration of aframe-group

preamble signaling data; signaling data carried by the preamble symboland used to identify the basic mode of the system

preamble symbol: fixed-length pilot symbol that carries basic PLS dataand is located in the beginning of a frame

NOTE: The preamble symbol is mainly used for fast initial band scan todetect the system signal, its timing, frequency offset, and FFT size.

reserved for future use: not defined by the present document but may bedefined in future

super frame: set of eight frame repetition units

time interleaving block (TI block): set of cells within which timeinterleaving is carried out, corresponding to one use of the timeinterleaver memory

TI group: unit over which dynamic capacity allocation for a particularDP is carried out, made up of an integer, dynamically varying number ofXFECBLOCKS

NOTE: The TI group may be mapped directly to one frame or may be mappedto multiple frames. It may contain one or more TI blocks.

Type 1 DP: DP of a frame where all DPs are mapped into the frame in TDMfashion

Type 2 DP: DP of a frame where all DPs are mapped into the frame in FDMfashion

XFECBLOCK: set of Ncells cells carrying all the bits of one LDPCFECBLOCK

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

The apparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can includean input formatting block 1000, a BICM (Bit interleaver coding &modulation) block 1010, a frame structure block 1020, an OFDM(Orthogonal Frequency Division Multiplexing) generation block 1030 and asignaling generation block 1040. A description will be given of theoperation of each module of the apparatus for transmitting broadcastsignals.

IP stream/packets and MPEG2-TS are the main input formats, other streamtypes are handled as General Streams. In addition to these data inputs,Management Information is input to control the scheduling and allocationof the corresponding bandwidth for each input stream, One or multiple TSstream(s), IP stream (s) and/or General Stream(s) inputs aresimultaneously allowed.

The input formatting block 1000 can demultiplex each input stream intoone or multiple data pipe(s), to each of which an independent coding andmodulation is applied. The data pipe (DP) is the basic unit forrobustness control, thereby affecting quality-of-service (QoS). One ormultiple service(s) or service component(s) can be carried by a singleDP. Details of operations of the input formatting block 1000 will bedescribed later.

The data pipe is a logical channel in the physical layer that carriesservice data or related metadata, which may carry one or multipleservice(s) or service component(s).

Also, the data pipe unit: a basic unit for allocating data cells to a DPin a frame.

In the BICM block 1010, parity data is added for error correction andthe encoded bit streams are mapped to complex-value constellationsymbols. The symbols are interleaver across a specific interleavingdepth that is used for the corresponding DP. For the advanced profile,MIMO encoding is performed in the BICM block 1010 and the additionaldata path is added at the output for MIMO transmission. Details ofoperations of the BICM block 1010 will be described later.

The Frame Building block 1020 can map the data cells of the input DPsinto the OFDM symbols within a frame. After mapping, the frequencyinterleaving is used for frequency-domain diversity, especially tocombat frequency-selective fading channels. Details of operations of theFrame Building block 1020 will be described later.

After inserting a preamble at the beginning of each frame, the OFDMGeneration block 1030 can apply conventional OFDM modulation having acyclic prefix as guard interval. For antenna space diversity, adistributed MISO scheme is applied across the transmitters. In addition,a Peak-to-Average Power Reduction (PAPR) scheme is performed in the timedomain. For flexible network planning, this proposal provides a set ofvarious FFT sizes, guard interval lengths and corresponding pilotpatterns. Details of operations of the OFDM Generation block 1030 willbe described later.

The Signaling Generation block 1040 can create physical layer signalinginformation used for the operation of each functional block. Thissignaling information is also transmitted so that the services ofinterest are properly recovered at the receiver side. Details ofoperations of the Signaling Generation block 1040 will be describedlater.

FIGS. 2, 3 and 4 illustrate the input formatting block 1000 according toembodiments of the present invention. A description will be given ofeach figure.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention. FIG. 2 shows an input formatting module whenthe input signal is a single input stream.

The input formatting block illustrated in FIG. 2 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

The input to the physical layer may be composed of one or multiple datastreams. Each data stream is carried by one DP. The mode adaptationmodules slice the Incoming data stream into data fields of the basebandframe (BBF). The system supports three types of input data streams:MPEG2-TS, internet protocol (IP) and Generic stream (GS), MPEG2-TS ischaracterized by fixed length (188 byte) packets with the first bytebeing a sync-byte (0×47). An IP stream is composed of variable length IPdatagram packets, as signaled within IP packet headers. The systemsupports both IPv4 and IPv6 for the IP stream. GS may be composed ofvariable length packets or constant length packets, signaled withinencapsulation packet headers.

(a) shows a mode adaptation block 2000 and a stream adaptation 2010 forsignal DP and (b) shows a PLS generation block 2020 and a PLS scrambler2030 for generating and processing PLS data. A description will be givenof the operation of each block.

The Input Stream Splitter splits the input TS, IP, GS streams intomultiple service or service component (audio, video, etc.) streams. Themode adaptation module 2010 is comprised of a CRC Encoder, BB (baseband)Frame Slicer, and BB Frame Header Insertion block.

The CRC Encoder provides three kinds of CRC encoding for error detectionat the user packet (UP) level, i.e., CRC-8, CRC-16, and CRC-32. Thecomputed CRC bytes are appended after the UP, CRC-8 is used for TSstream and CRC-32 for IP stream, if the GS stream doesn't provide theCRC encoding, the proposed CRC encoding should be applied.

BB Frame Slicer maps the input into an internal logical-bit format. Thefirst received bit is defined to be the MSB. The BB Frame Slicerallocates a number of input bits equal to the available data fieldcapacity. To allocate a number of input bits equal to the BBF payload,the UP packet stream is sliced to fit the data field of BBF.

BB Frame Header Insertion block can insert fixed length BBF header of 2bytes is inserted in front of the BB Frame. The BBF header is composedof STUFF1 (1 bit), SYNCD (13 bits), and RFU (2 bits). In addition to thefixed 2-Byte BBF header, BBF can have an extension field (1 or 3 bytes)at the end of the 2-byte BBF header.

The stream adaptation 2010 is comprised of stuffing insertion block andBB scrambler.

The stuffing insertion block can insert stuffing field into a payload ofa BB frame. If the input data to the stream adaptation is sufficient tofill a BB-Frame, STUFF1 is set to ‘0’ and the BBF has no stuffing field.Otherwise STUFF1 is set to ‘1’ and the stuffing field is insertedimmediately after the BBF header. The stuffing field comprises two bytesof the stuffing field header and a variable size of stuffing data.

The BB scrambler scrambles complete BBF for energy dispersal. Thescrambling sequence is synchronous with the BBF. The scrambling sequenceis generated by the feed-back shift register.

The PLS generation block 2020 can generate physical layer signaling(PLS) data. The PLS provides the receiver with a means to accessphysical layer DPs. The PLS data consists of PLS1 data and PLS2 data.

The PLS1 data is a first set of PLS data carried in the FSS symbols inthe frame having a fixed size, coding and modulation, which carriesbasic information about the system as well as the parameters needed todecode the PLS2 data. The PLS1 data provides basic transmissionparameters including parameters required to enable the reception anddecoding of the PLS2 data. Also, the PLS1 data remains constant for theduration of a frame-group.

The PLS2 data is a second set of PLS data transmitted in the FSS symbol,which carries more detailed PLS data about the system and the DPs. ThePLS2 contains parameters that provide sufficient information for thereceiver to decode the desired DP. The PLS2 signaling further consistsof two types of parameters, PLS2 Static data (PLS2-STAT data) and PLS2dynamic data (PLS2-DYN data). The PLS2 Static data is PLS2 data thatremains static for the duration of a frame-group and the PLS2 dynamicdata is PLS2 data that may dynamically change frame-by-frame.

Details of the PLS data will be described later.

The PLS scrambler 2030 can scramble the generated PLS data for energydispersal.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 3 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 3 shows a mode adaptation block of the input formatting block whenthe input signal corresponds to multiple input streams.

The mode adaptation block of the input formatting block for processingthe multiple input streams can independently process the multiple inputstreams.

Referring to FIG. 3, the mode adaptation block for respectivelyprocessing the multiple input streams can include an input streamsplitter 3000, an input stream synchronizer 3010, a compensating delayblock 3020, a null packet deletion block 3030, a head compression block3040, a CRC encoder 3050, a BB frame slicer 3060 and a BQ headerinsertion block 3070. Description will be given of each block of themode adaptation block.

Operations of the CRC encoder 3050, BB frame slicer 3060 and BB headerinsertion block 3070 correspond to those of the CRC encoder, BB frameslicer and BB header insertion block described with reference to FIG. 2and thus description thereof is omitted.

The input stream splitter 3000 can split the input TS, IP, GS streamsinto multiple service or service component (audio, video, etc.) streams.

The input stream synchronizer 3010 may be referred as ISSY. The 1SSY canprovide suitable means to guarantee Constant Bit Rate (CBR) and constantend-to-end transmission delay for any input data format. The ISSY isalways used for the case of multiple DPs carrying TS, and optionallyused for multiple DPs carrying GS streams.

The compensating delay block 3020 can delay the split TS packet streamfollowing the insertion of ISSY information to allow aTS packetrecombining mechanism without requiring additional memory in thereceiver.

The null packet deletion block 3030, is used only for the TS inputstream case. Some TS input streams or split TS streams may have a largenumber of null-packets present in order to accommodate VBR (variablebit-rate) services in a CBR TS stream. In this case, in order to avoidunnecessary transmission overhead, null-packets can be identified andnot transmitted. In the receiver, removed null-packets can bere-inserted in the exact place where they were originally by referenceto a deleted null-packet (DNP) counter that IS inserted in thetransmission, thus guaranteeing constant bit-rate and avoiding the needfor time-stamp (PCR) updating.

The head compression block 3040 can provide packet header compression toincrease transmission efficiency for TS or IP input streams. Because thereceiver can have a priori information on certain parts of the header,this known information can be deleted in the transmitter.

For Transport. Stream, the receiver has a-priori information about thesync-byte configuration (0×47) and the packet length (188 Byte). If theinput TS stream carries content that has only one PID, i.e., for onlyone service component (video, audio, etc.) or service sub-component (SVCbase layer, SVC enhancement layer, MVC base view or MVC dependentviews), TS packet header compression can be applied (optionally) to theTransport Stream. IP packet header compression is used optionally if theinput steam is an IP stream.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 4 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 4 illustrates a stream adaptation block of the input formattingmodule when the input signal corresponds to multiple input streams.

Referring to FIG. 4, the mode adaptation block for respectivelyprocessing the multiple input streams can include a scheduler 4000, an1-Frame delay block 4010, a stuffing insertion block 4020, an in-bandsignaling 4030, a BB Frame scrambler 4040, a PLS generation block 4050and a PLS scrambler 4060. Description will be given of each block, ofthe stream adaptation block.

Operations of the stuffing insertion block 4020, the BB Frame scrambler4040, the PLS generation block 4050 and the PLS scrambler 4060correspond to those of the stuffing insertion block, BB scrambler, PLSgeneration block and the PLS scrambler described with reference to FIG.2 and thus description thereof is omitted.

The scheduler 4000 can determine the overall cell allocation across theentire frame from the amount of FECBLOCKs of each DP. Including theallocation for PLS, EAC and FIC, the scheduler generate the values ofPLS2-DYN data, which is transmitted as in-band signaling or PLS cell inFSS of the frame. Details of FECBLOCK, EAC and FIC will be describedlater.

The 1-Frame delay block 4010 can delay the input data by onetransmission frame such that scheduling information about the next framecan be transmitted through the current frame for in-band signalinginformation to be inserted into the DPs.

The in-band signaling 4030 can insert un-delayed part of the PLS2 datainto a DP of a frame.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

The BICM block illustrated in FIG. 5 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

As described above, the apparatus for transmitting broadcast signals forfuture broadcast services according to an embodiment of the presentinvention can provide a terrestrial broadcast service, mobile broadcastservice, UHDTV service, etc.

Since QoS (quality of service) depends on characteristics of a serviceprovided by the apparatus for transmitting broadcast signals for futurebroadcast services according to air embodiment of the present invention,data corresponding to respective services needs to be processed throughdifferent schemes. Accordingly, the a BICM block according to anembodiment of the present invention can independently process DPs inputthereto by independently applying SISO, MTSO and MIMO schemes to thedata pipes respectively corresponding to data paths. Consequently, theapparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can controlQoS for each service or service component transmitted through each DP.

(a) shows the BICM block shared by the base profile and the handheldprofile and (b) shows the BICM block of the advanced profile.

The BICM block shared by the base profile and the handheld profile andthe BICM block of the advanced profile can include plural processingblocks for processing each DP.

A description will be given of each processing block of the BICM blockfor the base profile and the handheld profile and the BICM block for theadvanced profile.

A processing block 5000 of the BICM block for the base profile and thehandheld profile can include a Data FEC encoder 5010, a bit interleaver5020, a constellation mapper 5030, an SSD (Signal Space Diversity)encoding block 5040 and a time interleaver 5050.

The Data FEC encoder 5010 can perform the FEC encoding on the input BBFto generate FECBLOCK procedure using outer coding (BCH), and innercoding (LDPC). The outer coding (BCH) is optional coding method, Detailsof operations of the Data FEC encoder 5010 will be described later.

The bit interleaver 5020 can interleave outputs of the Data FEC encoder5010 to achieve optimized performance with combination of the LDPC codesand modulation scheme while providing an efficiently implementablestructure. Details of operations of the bit interleaver 5020 will bedescribed later.

The constellation mapper 5030 can modulate each cell word from the bitinterleaver 5020 in the base and the handheld profiles, or cell wordfrom the Cell-word demultiplexer 5010-1 in the advanced profile usingeither QPSK, QAM-16, non-uniform QAM (NUQ-64, NUQ-256, NUQ-1024) ornon-uniform constellation (NUC-16, NUC-64, NUC-256, NUC-1024) to give apower-normalized constellation point, el. This constellation mapping isapplied only for DPs. Observe that QAM-16 and NUQs are square shaped,while NUCs have arbitrary shape. When each constellation is rotated byany multiple of 90 degrees, the rotated constellation exactly overlapswith its original one. This “rotation-sense” symmetric property makesthe capacities and the average powers of the real and imaginarycomponents equal to each other. Both NUQs and NUCs are definedspecifically for each code rate and the particular one used is signaledby the parameter DP_MOD filed in PLS2 data.

The SSD encoding block 5040 can precode cells in two (2D), three (3D),and four (4D) dimensions to increase the reception robustness underdifficult fading conditions.

The time interleaver 5050 can operates at the DP level. The parametersof time interleaving (TI) may be set differently for each DP. Details ofoperations of the time interleaver 5050 will be described later.

A processing block 5000-1 of the BICM block for the advanced profile caninclude the Data FEC encoder, bit interleaver, constellation mapper, andtime interleaver. However, the processing block 5000-1 is distinguishedfrom the processing block 5000 further includes a cell-worddemultiplexer 5010-1 and a MIMC) encoding block 5020-1.

Also, the operations of the Data FEC encoder, bit interleaver,constellation mapper, and time interleaver in the processing block5000-1 correspond to those of the Data FEC encoder 5010, bit interleaver5020, constellation mapper 5030, and time interleaver 5050 described andthus description thereof is omitted.

The cell-word demultiplexer 5010-1 is used for the DP of the advancedprofile to divide the single cell-word stream into dual cell-wordstreams for MIMO processing. Details of operations of the cell-worddemultiplexer 5010-1 will be described later.

The MIMO encoding block 5020-1 can processing the output of thecell-word demultiplexer 5010-1 using MIMO encoding scheme. The MIMOencoding scheme was optimized for broadcasting signal transmission. TheMIMO technology is a promising way to get a capacity increase but itdepends on channel characteristics. Especially for broadcasting, thestrong LOS component of the channel or a difference in the receivedsignal power between two antennas caused by different signal propagationcharacteristics makes it difficult to get capacity gain from MIMO. Theproposed MIMO encoding scheme overcomes this problem using arotation-based pre-coding and phase randomization of one of the MIMOoutput signals.

MIMO encoding is intended for a 2×2 MIMO system requiring at least twoantennas at both the transmitter and the receiver. Two MIMO encodingmodes are defined in this proposal; full-rate spatial multiplexing(FR-SM) and full-rate full-diversity spatial multiplexing (FRFD-SM). TheFR-SM encoding provides capacity increase with relatively smallcomplexity increase at the receiver side while the FRFD-SM encodingprovides capacity increase and additional diversity gain with a greatcomplexity increase at the receiver side. The proposed MIMO encodingscheme has no restriction on the antenna polarity configuration.

MIMO processing is required for the advanced profile frame, which meansall DPs in the advanced profile frame are processed by the MIMO encoder,MIMO processing is applied at DP level. Pairs of the ConstellationMapper outputs NUQ (e1, i and e2,i) are fed to the input of the MIMOEncoder. Paired MIMO Encoder output (g1.i and g2,i) is transmitted bythe same carrier k and OFDM symbol 1 of their respective TX antennas.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

The BICM block illustrated in FIG. 6 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

FIG. 6 illustrates a BICM block for protection of physical layersignaling (PLS), emergency alert channel (EAC) and fast informationchannel (FIC). EAC is a part of a frame that carries EAS informationdata and FIC is a logical channel in a frame that carries the mappinginformation between a service and the corresponding base DP, Details ofthe EAC and FIC will be described later.

Referring to FIG. 6, the BICM block for protection of PLS, EAC and FICcan include a PLS FEC encoder 6000, a bit interleaver 6010 and aconstellation mapper 6020.

Also, the PLS FEC encoder 6000 can include a scrambler, BCHencoding/zero insertion block, LDPC encoding block and LDPC paritypunturing block. Description will be given of each block of the BICMblock.

The PLS FEC encoder 6000 can encode the scrambled PLS 1/2 data, EAC andFIC section.

The scrambler can scramble PLS1 data and PLS2 data before BCH encodingand shortened and punctured LDPC encoding.

The BCH encoding/zero insertion block can perform outer encoding on thescrambled PLS 1/2 data using the shortened BCH code for PLS protectionand insert zero bits after the BCH encoding. For PLS1 data only, theoutput bits of the zero insertion may be permitted before LDPC encoding.

The LDPC encoding block can encode the output of the BCH encoding/zeroinsertion block using LDPC code. To generate a complete coded block,Cldpc, parity bits, Pldpc are encoded systematically from eachzero-inserted PLS information block, Ildpc and appended after it.

C _(idpc) =[I _(idpc) P _(ldpc) ]=[i ₀ , i ₁ , . . . , i _(k) _(ldpc) ⁻¹, p ₀ ,p ₁ , . . . , p _(N) _(ldpc) _(−k) _(ldpc) _(−1])  Math Figure 1

The LDPC code parameters for PLS1 and PLS2 are as following table 4.

TABLE 4 Signal- ing N_(bch)_ K_(ldpc) code Type K_(sig) K_(bch)_(parity) (=N_(bch)) N_(ldpc) N_(ldpc)_parity rate Q_(ldpc) PLS1 3421020 60 1080 4320 3240 1/4  36 PLS2 <1021 <1020 2100 2160 7200 5040 3/1056

The LDPC parity punturing block can perform puncturing on the PLS1 dataand PLS 2 data.

When shortening is applied to the PLS1 data protection, some LDPC paritybits are punctured after LDPC encoding. Also, for the PLS2 dataprotection, the LDPC parity bits of PLS2 are punctured after LDPCencoding. These punctured bits are not transmitted.

The bit interleaver 6010 can interleave the each shortened and puncturedPLS1 data and PLS2 data.

The constellation mapper 6020 can map the bit ineterlaeved PLS1 data andPLS2 data onto constellations.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention,

The frame building block illustrated in FIG. 7 corresponds to anembodiment of the frame building block 1020 described with reference toFIG. 1.

Referring to FIG. 7, the frame building block can include a delaycompensation block 7000, a cell mapper 7010 and a frequency interleaver7020. Description will be given of each block of the frame buildingblock.

The delay compensation block 7000 can adjust the timing between the datapipes and the corresponding PLS data to ensure that they are co-timed atthe transmitter end. The PLS data is delayed by the same amount as datapipes are by addressing the delays of data pipes caused by the InputFormatting block and BICM block. The delay of the BICM block is mainlydue to the time interleaver 5050. In-band signaling data carriesinformation of the next TI group so that they are carried one frameahead of the DPs to be signaled. The Delay Compensating block delaysin-band signaling data accordingly.

The cell mapper 7010 can map PLS, EAC, FIC, DPs, auxiliary streams anddummy cells into the active carriers of the OFDM symbols in the frame.The basic function of the cell mapper 7010 is to map data cells producedby the TI s for each of the DPs, PLS cells, and EAC/FIC cells, if any,into arrays of active OFDM cells corresponding to each of the OFDMsymbols within a frame. Service signaling data (such as PSI(programspecific information)/SI) can be separately gathered and sent by a datapipe. The Cell Mapper operates according to the dynamic informationproduced by the scheduler and the configuration of the frame structure.Details of the frame will be described later.

The frequency Interleaver 7020 can randomly interleave data cellsreceived from the cell mapper 7010 to provide frequency diversity. Also,the frequency interleaver 7020 can operate on very OFDM symbol paircomprised of two sequential OFDM symbols using a differentinterleaving-seed order to get maximum interleaving gain in a singleframe.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 8 illustrates art OFDM generation block according to an embodimentof the present invention.

The OFDM generation block illustrated in FIG. 8 corresponds to anembodiment of the OFDM generation block 1030 described with reference toFIG. 1.

The OFDM generation block modulates the OFDM carriers by the cellsproduced by the Frame Building block, inserts the pilots, and producesthe time domain signal for transmission. Also, this block subsequentlyinserts guard intervals, and applies PAPR (Peak-to-Average Power Radio)reduction processing to produce the final RF signal.

Referring to FIG. 8, the frame building block can include a pilot andreserved tone insertion block 8000, a 2D-cSFN encoding block 8010, anIFFT (Inverse Fast Fourier Transform) block 8020, a PAPR reduction block8030, a guard interval insertion block 8040, a preamble insertion block8050, other system insertion block 8060 and a DAC block 8070,Description will be given of each block of the frame building block.

The pilot and reserved tone insertion block 8000 can insert pilots andthe reserved tone.

Various cells within the OFDM symbol are modulated with referenceinformation, known as pilots, which have transmitted values known apriori in the receiver. The information of pilot cells is made up ofscattered pilots, continual pilots, edge pilots, FSS (frame signalingsymbol) pilots and FES (frame edge symbol) pilots. Each pilot istransmitted at a particular boosted power level according to pilot typeand pilot pattern. The value of the pilot information is derived from areference sequence, which is a series of values, one for eachtransmitted carrier on any given symbol. The pilots can be used forframe synchronization, frequency synchronization, time synchronization,channel estimation, and transmission mode identification, and also canbe used to follow the phase noise.

Reference information, taken from the reference sequence, is transmittedin scattered pilot cells in every symbol except the preamble, FSS andFES of the frame. Continual pilots are inserted in every symbol of theframe. The number and location of continual pilots depends on both theFFT size and the scattered pilot pattern. The edge carriers are edgepilots in every symbol except for the preamble symbol. They are insertedin order to allow frequency Interpolation up to the edge of thespectrum. FSS pilots are inserted in FSS(s) and FES pilots are insertedin FES. They are inserted in order to allow time interpolation up to theedge of the frame.

The system according to an embodiment of the present invention supportsthe SFN network, where distributed MISO scheme is optionally used tosupport very robust transmission mode. The 2D-eSFN is a distributed MISOscheme that uses multiple TX antennas, each of which is located in thedifferent transmitter site in the SFN network.

The 2D-eSFN encoding block 8010 can process a 2D-eSFN processing todistorts the phase of the signals transmitted from multipletransmitters, in order to create both time and frequency diversity inthe SFN configuration. Hence, burst errors due to low flat fading ordeep-fading for a long time can be mitigated.

The TFFT block 8020 can modulate the output from the 2D-eSFN encodingblock 8010 using OFDM modulation scheme. Any cell in the data symbolswhich has not been designated as a pilot (or as a reserved tone) carriesone of the data cells from the frequency Interleaver. The cells aremapped to OFDM carriers.

The PAPR reduction block 8030 can perform a PAPR reduction on inputsignal using various PAPR reduction algorithm in the time domain.

The guard interval insertion block 8040 can insert guard intervals andthe preamble insertion block 8050 can insert preamble in front of thesignal. Details of a structure of the preamble will be described later.The other system insertion block 8060 can multiplex signals of aplurality of broadcast transmission/reception systems in the time domainsuch that data of two or more different broadcast transmission/receptionsystems providing broadcast services can be simultaneously transmittedin the same RF signal bandwidth. In this case, the two or more differentbroadcast transmission/reception systems refer to systems providingdifferent broadcast services. The different broadcast services may referto a terrestrial broadcast service, mobile broadcast service, etc. Datarelated to respective broadcast services can be transmitted throughdifferent frames.

The DAC block 8070 cars convert an input digital signal into an analogsignal and output the analog signal. The signal output from the DACblock 7800 can be transmitted through multiple output antennas accordingto the physical layer profiles. A Tx antenna according to an embodimentof the present invention can have vertical or horizontal polarity.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention cancorrespond to the apparatus for transmitting broadcast signals forfuture broadcast services, described with reference to FIG. 1.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention can includea synchronization & demodulation module 9000, a frame parsing module9010, a demapping & decoding module 9020, an output processor 9030 and asignaling decoding module 9040. A description will be given of operationof each module of the apparatus for receiving broadcast signals.

The synchronization & demodulation module 9000 can receive input signalsthrough m Rx antennas, perform signal detection and synchronization withrespect to a system corresponding to the apparatus for receivingbroadcast signals and carry out demodulation corresponding to a reverseprocedure of the procedure performed by the apparatus for transmittingbroadcast signals.

The frame parsing module 9100 can parse input signal frames and extractdata through which a service selected by a user is transmitted. If theapparatus for transmitting broadcast signals performs interleaving, theframe parsing module 9100 can carry out deinterleaving corresponding toa reverse procedure of interleaving. In this case, the positions of asignal and data that need to be extracted can be obtained by decodingdata output from the signaling decoding module 9400 to restorescheduling information generated by the apparatus for transmittingbroadcast signals.

The demapping & decoding module 9200 can convert the input signals intobit domain data and then deinterleave the same as necessary. Thedemapping & decoding module 9200 can perform demapping for mappingapplied for transmission efficiency and correct an error generated on atransmission channel through decoding. In this case, the demapping &decoding module 9200 can obtain transmission parameters necessary fordemapping and decoding by decoding the data output from the signalingdecoding module 9400.

The output processor 9300 can perform reverse procedures of variouscompression/signal processing procedures which are applied by theapparatus for transmitting broadcast signals to improve transmissionefficiency. In this case, the output processor 9300 can acquirenecessary control information from data output from the signalingdecoding module 9400. The output of the output processor 8300corresponds to a signal Input to the apparatus for transmittingbroadcast signals and may be MPEG-TSs, IP streams (v4 or v6) and genericstreams.

The signaling decoding module 9400 can obtain PLS information from thesignal demodulated by the synchronization & demodulation module 9000. Asdescribed above, the frame parsing module 9100, demapping & decodingmodule 9200 and output processor 9300 can execute functions thereofusing the data output from the signaling decoding module 9400.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 10 shows an example configuration of the frame types and FRUs in asuper-frame. (a) shows a super frame according to an embodiment of thepresent invention, (b) shows FRU (Frame Repetition Unit) according to anembodiment of the present invention, (c) shows frames of variable PHYprofiles in the FRU and (d) shows a structure of a frame.

A super-frame may be composed of eight FRUs. The FRU is a basicmultiplexing unit for TDM of the frames, and is repeated eight times ina super-frame.

Each frame in the FRU belongs to one of the PHY profiles, (base,handheld, advanced) or FEF. The maximum allowed number of the frames inthe FRU is four and a given PHY profile can appear any number of timesfrom zero times to four times in the FRU (e.g., base, base, handheld,advanced). PHY profile definitions can be extended using reserved valuesof the PHY_PROFILE in the preamble, if required.

The FEF part is inserted at the end of the FRU, if included. When theFEF is included in the FRU, the minimum number of FEFs is 8 in asuper-frame. It is not recommended that FEF parts be adjacent to eachother.

One frame is further divided into a number of OFDM symbols and apreamble. As shown in (d), the frame comprises a preamble, one or moreframe signaling symbols (FSS), normal data symbols and a frame edgesymbol (FES).

The preamble is a special symbol that enables fast Futurecast UTB systemsignal detection and provides a set of basic transmission parameters forefficient transmission and reception of the signal. The detaileddescription of the preamble will be will be described later.

The main purpose of the FSS(s) is to carry the PLS data. For fastsynchronization and channel estimation, and hence fast decoding of PLSdata, the FSS has more dense pilot pattern than the normal data symbol.The FES has exactly the same pilots as the FSS, which enablesfrequency-only interpolation within the FES and temporal interpolation,without extrapolation, for symbols immediately preceding the FES.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 11 illustrates the signaling hierarchy structure, which is splitInto three main parts; the preamble signaling data 11000, the PLS1 data11010 and the PLS2 data 11020. The purpose of the preamble, which iscarried by the preamble symbol in every frame, is to indicate thetransmission type and basic transmission parameters of that frame. ThePLS1 enables the receiver to access and decode the PLS2 data, whichcontains the parameters to access the DP of interest The PLS2 is carriedin every frame and split into two main parts: PLS2-STAT data andPLS2-DYN data. The static and dynamic portion of PLS2 data is followedby padding, if necessary.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

Preamble signaling data carries 21 bits of information that are neededto enable the receiver to access PLS data and trace DPs within the framestructure. Details of the preamble signaling data are as follows:

PHY PROFILE: This 3-bit field indicates the PHY profile type of thecurrent frame. The mapping of different PHY profile types is given inbelow table 5.

TABLE 5 Signal- ing N_(bch)_ K_(ldpc) code Type K_(sig) K_(bch)_(parity) (=N_(bch)) N_(ldpc) N_(ldpc)_parity rate Q_(ldpc) PLS1 3421020 60 1080 4320 3240 1/4  36 PLS2 <1021 <1020 2100 2160 7200 5040 3/1056

FFT_SIZE; This 2 bit field indicates the FFT size of the current framewithin a frame-group, as described in below table 6.

TABLE 6 Value FFT size 00  8K FFT 01 16K FFT 10 32K FFT 11 Reserved

GI_FRACTION: This 3 bit field indicates the guard interval fractionvalue in the current super-frame, as described in below table 7.

TABLE 7 Value GI_FRACTION 000 1/5  001 1/10 010 1/20 011 1/40 100 1/80101  1/160 110~111 Reserved

EAC_FLAG: This 1 bit field indicates whether the EAC is provided in thecurrent frame. If this field is set to ‘1’, emergency alert service(EAS) is provided in the current frame. If this field set to ‘0’, EAS isnot carried in the current frame. This field can be switched dynamicallywithin a super-frame.

PILOT MODE: This 1 -bit field indicates whether the pilot mode is mobilemode or fixed mode for the current frame in the current frame-group. Ifthis field is set to ‘0’, mobile pilot mode is used. If the field is setto ‘1’, the fixed pilot mode is used.

PAPR_FLAG: This 1-bit field indicates whether PAPR reduction is used forthe current frame in the current frame-group. If this field is set tovalue ‘1’, tone reservation is used for PAPR reduction. If this field isset to ‘0’, PAPR reduction is not used.

FRU_CONFIGURE: This 3-bit field indicates the PHY profile typeconfigurations of the frame repetition units (FRU) that are present inthe current super-frame. All profile types conveyed in the currentsuper-frame are identified in this field in all preambles in the currentsuper-frame. The 3-bit field has a different definition for eachprofile, as show in below table 8.

TABLE 8 Current Current Current Current PHY_PROFILE = PHY_PROFILE =PHY_PROFILE = PHY_PROFILE = ‘000’ (base) ‘001’ (handheld) ‘010’(advanced) ‘111’ (FEF) FRU_CONFIGURE = Only base Only handheld Onlyadvanced Only FEF 000 profile present profile present profile presentpresent FRU_CONFIGURE = Handheld Base profile Base profile Base profile1XX profile present present present present FRU_CONFIGURE = AdvancedAdvanced Handheld Handheld X1X profile profile profile profile presentpresent present present FRU_CONFIGURE = FEF FEF FEF Advanced XX1 presentpresent present profile present

RESERVED: This 7-bit field is reserved for future use.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

PLS1 data provides basic transmission parameters including parametersrequired to enable the reception and decoding of the PLS2. As abovementioned, the PLS1 data remain unchanged for the entire duration of oneframe-group. The detailed definition of the signaling fields of the PLS1data are as follows:

PREAMBLE_DATA: This 20-bit field is a copy of the preamble signalingdata excluding the EAC_FLAG.

NUM_FRAME_FRU: This 2-bit field indicates the number of the frames perFRU.

PAYLOAD_TYPE: This 3-bit field indicates the format of the payload datacarried in the frame-group. PAYLOAD_TYPE is signaled as shown in table9.

TABLE 9 Current Current Current Current PHY_PROFILE = PHY_PROFILE =PHY_PROFILE = PHY_PROFILE = ‘000’ (base) ‘001’ (handheld) ‘010’(advanced) ‘111’ (FEF) FRU_CONFIGURE = Only base Only handheld Onlyadvanced Only FEF 000 profile present profile present profile presentpresent FRU_CONFIGURE = Handheld Base profile Base profile Base profile1XX profile present present present present FRU_CONFIGURE = AdvancedAdvanced Handheld Handheld X1X profile profile profile profile presentpresent present present FRU_CONFIGURE = FEF FEF FEF Advanced XX1 presentpresent present profile present

NUM _FSS: This 2-bit field indicates the number of FSS symbols in thecurrent frame.

SYSTEM_VERSION: This 8-bit field indicates the version of thetransmitted signal format. The SYSTEM_VERSION is divided into two 4-bitfields, which are a major version and a minor version.

Major version: The MSB four bits of SYSTEM_VERSION field indicate majorversion information. A change in the major version field indicates anon-backward-compatible change. The default value is ‘0000’. For theversion described in this standard, the value is set to ‘0000’.

Minor version: The LSB four bits of SYSTEM_VERSION field indicate minorversion information. A change in the minor version field isbackward-compatible.

CELL_ID: This is a 16-bit field which uniquely identifies a geographiccell in an ATSC network. An ATSC cell coverage area may consist of oneor more frequencies, depending on the number of frequencies used perFuturecast UTB system. If the value of the CELL_ID is not known orunspecified, this field is set to ‘0’.

NETWORK_ID: This is a 16-bit field which uniquely identifies the currentATSC network.

SYSTEM_ID: This 16-bit field uniquely identifies the Futurecast UTBsystem within the ATSC network. The Futurecast UTB system is theterrestrial broadcast system whose input is one or more input streams(TS, IP, GS) and whose output is an RF signal. The Futurecast UTB systemcarries one or more PHY profiles and FEF, if any. The same FuturecastUTB system may carry different input streams and use different RFfrequencies in different geographical areas, allowing local serviceinsertion. The frame structure and scheduling is controlled in one placeand is identical for all transmissions within a Futurecast UTB system.One or more Futurecast UTB systems may have the same SYSTEM_ID meaningthat they all have the same physical layer structure and configuration.

The following loop consists of FRU_PHY_PROFILE, FR U_FRAME_LENGTH,FRU_GI _FRACTION, and RESERVED which are used to indicate the FRUconfiguration and the length of each frame type. The loop size is fixedso that four PHY profiles (including a FEF) are signaled within the FRU.If NUM_FRAME_FRU is less than 4, the unused fields are filled withzeros.

FRU_PHY_PROFILE: This 3-bit field indicates the PHY profile type of the(i+1)th (i is the loop index) frame of the associated FRU. This fielduses the same signaling format as shown in the table 8.

FRU_FRAME_LENGTH: This 2-bit field indicates the length of the (i+1)thframe of the associated FRU, Using FRU_FRAME_LENGTH together withFRU_GI_FRACTION, the exact value of the frame duration can be obtained.

FRU_GI_FRACTION: This 3-bit field indicates the guard interval fractionvalue of the (i+1)th frame of the associated FRU, FRU_GI_FRACTION issignaled according to the table 7.

RESERVED: This 4-bit field is reserved for future use.

The following fields provide parameters for decoding the PLS2 data.

PLS2_FEC_TYPE: This 2-bit field indicates the FEC type used by the PLS2protection. The FEC type is signaled according to table 10. The detailsof the LDPC codes will be described later.

TABLE 10 Current Current Current Current PHY_PROFILE = PHY_PROFILE =PHY_PROFILE = PHY_PROFILE = ‘000’ (base) ‘001’ (handheld) ‘010’(advanced) ‘111’ (FEF) FRU_CONFIGURE = Only base Only handheld Onlyadvanced Only FEF 000 profile present profile present profile presentpresent FRU_CONFIGURE = Handheld Base profile Base profile Base profile1XX profile present present present present FRU_CONFIGURE = AdvancedAdvanced Handheld Handheld X1X profile profile profile profile presentpresent present present FRU_CONFIGURE = FEF FEF FEF Advanced XX1 presentpresent present profile present

PLS2_MOD: This 3-bit field indicates the modulation type used by thePLS2. The modulation type is signaled according to table 11.

TABLE 11 Current Current Current Current PHY_PROFILE = PHY_PROFILE =PHY_PROFILE = PHY_PROFILE = ‘000’ (base) ‘001’ (handheld) ‘010’(advanced) ‘111’ (FEF) FRU_CONFIGURE = Only base Only handheld Onlyadvanced Only FEF 000 profile present profile present profile presentpresent FRU_CONFIGURE = Handheld Base profile Base profile Base profile1XX profile present present present present FRU_CONFIGURE = AdvancedAdvanced Handheld Handheld X1X profile profile profile profile presentpresent present present FRU_CONFIGURE = FEF FEF FEF Advanced XX1 presentpresent present profile present

PLS2_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block, thesize (specified as the number of QAM cells) of the collection of fullcoded blocks for PLS2 that is carried in the current frame-group. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, ofthe PLS2-STAT for the current frame-group. This value is constant duringthe entire duration of the current frame-group.

PLS2_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of thePLS2-DYN for the current frame-group. This value is constant during theentire duration of the current frame-group.

PLS2 REP FLAG: This 1-bit flag indicates whether the PLS2 repetitionmode is used in the current frame-group. When this field is set to value‘1’, the PLS2 repetition mode is activated. When this field is set tovalue ‘0’, the PLS2 repetition mode is deactivated.

PLS2_REP_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block,the size (specified as the number of QAM cells) of the collection ofpartial coded blocks for PLS2 carried in every frame of the currentframe-group, when PLS2 repetition is used. If repetition is not used,the value of this field is equal to 0. This value is constant during theentire duration of the current frame-group.

PLS2_NEXT_FEC_TYPE: This 2-bit field indicates the FEC type used forPLS2 that is carried in every frame of the next frame-group. The FECtype is signaled according to the table 10.

PLS2_NEXT_MOD: This 3-bit field Indicates the modulation type used forPLS2 that is carried in every frame of the next frame-group. Themodulation type is signaled according to the table 11.

PLS2_NEXT_REP_FLAG: This 1 -bit flag indicates whether the PLS2repetition mode is used in the next frame-group. When this field is setto value ‘1’, the PLS2 repetition mode is activated. When this field isset to value ‘0’, the PLS2 repetition mode is deactivated.

PLS2_NEXT_REP_SIZE_CELL: This 15-bit field indicates Ctotal_full_block,The size (specified as the number of QAM cells) of the collection offull coded blocks for PLS2 that is carried in every frame of the nextframe-group, when PLS2 repetition is used. If repetition is not used inthe next frame-group, the value of this field is equal to 0. This valueis constant during the entire duration of the current frame-group.

PLS2_NEXT_REP_STAT_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-STAT for the next frame-group. This value is constantin the current, frame-group.

PLS2_NEXT_REP_DYN_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-DYN for the next frame-group. This value is constantin the current frame-group.

PLS2 AP MODE: This 2-bit field indicates whether additional parity isprovided for PLS2 in the current frame-group. This value is constantduring the entire duration of the current frame-group. The below table12 gives the values of this field. When this field is set to ‘00’,additional parity is not used for the PLS2 in the current frame-group.

TABLE 12 Current Current Current Current PHY_PROFILE = PHY_PROFILE =PHY_PROFILE = PHY_PROFILE = ‘000’ (base) ‘001’ (handheld) ‘010’(advanced) ‘111’ (FEF) FRU_CONFIGURE = Only base Only handheld Onlyadvanced Only FEF 000 profile present profile present profile presentpresent FRU_CONFIGURE = Handheld Base profile Base profile Base profile1XX profile present present present present FRU_CONFIGURE = AdvancedAdvanced Handheld Handheld X1X profile profile profile profile presentpresent present present FRU_CONFIGURE = FEF FEF FEF Advanced XX1 presentpresent present profile present

PLS2_AP_SIZE_CELL: This 15-bit field indicates the size (specified asthe number of QAM cells) of the additional parity bits of the PLS2. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_NEXT_AP_MODE: This 2-bit field indicates whether additional parityis provided for PLS2 signaling in e very frame of next frame-group. Thisvalue is constant during the entire duration of the current frame-group.The table 12 defines the values of this field

PLS2_NEXT_AP_SIZE_CELL: This 15-bit field indicates the size (specifiedas the number of QAM cells) of the additional parity bits of the PLS2 inevery frame of the next frame-group. This value is constant during theentire duration of the current frame-group.

RESERVED: This 32-bit field is reserved for future use.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS1 signaling.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2-STAT data of the PLS2 data. The PLS2-STAT dataare the same within a frame-group, while the PLS2-DYN data provideinformation that is specific for the current frame.

The details of fields of the PLS2-STAT data are as follows:

FIC_FLAG: This 1-bit field indicates whether the FIC is used in thecurrent frame-group. If this field is set to ‘1’, the FIC is provided inthe current frame. If this field set to ‘0’, the FIC is not carried inthe current frame. This value is constant during the entire duration ofthe current frame-group.

AUX_FLAG: This 1-bit field indicates whether the auxiliary stream(s) isused in the current frame-group. If this field is set to ‘1’, theauxiliary stream is provided in the current frame. If this field set to‘0’, the auxiliary stream is not carried in the current frame. Thisvalue is constant during the entire duration of current frame-group.

NUM_DP: This 6-bit field indicates the number of DPs carried within thecurrent frame. The value of this field ranges from 1 to 64, and thenumber of DPs is NUM_DP+1.

DP_ID: This 6-bit field identifies uniquely a DP within a PHY profile.

DP_TYPE: This 3-bit field indicates the type of the DP. This is signaledaccording to the below table 13.

TABLE 13 Current Current Current Current PHY_PROFILE = PHY_PROFILE =PHY_PROFILE = PHY_PROFILE = ‘000’ (base) ‘001’ (handheld) ‘010’(advanced) ‘111’ (FEF) FRU_CONFIGURE = Only base Only handheld Onlyadvanced Only FEF 000 profile present profile present profile presentpresent FRU_CONFIGURE = Handheld Base profile Base profile Base profile1XX profile present present present present FRU_CONFIGURE = AdvancedAdvanced Handheld Handheld X1X profile profile profile profile presentpresent present present FRU_CONFIGURE = FEF FEF FEF Advanced XX1 presentpresent present profile present

DP_GROUP_ID: This 8-bit field identifies the DP group with which thecurrent DP is associated. This can be used by a receiver to access theDPs of the service components associated with a particular service,which will have the same DP_GROUP_ID.

BASE_DP_ID: This 6-bit field indicates the DP carrying service signalingdata (such as PS1/S1) used in the Management layer. The DP indicated byBASE_DP_1D may be either a normal DP carrying the service signaling dataalong with the service data or a dedicated DP carrying only the servicesignaling data

DP_FEC_TYPE: This 2-bit field Indicates the FEC type used by theassociated DP. The FEC type is signaled according to the below table 14.

TABLE 14 Value FEC_TYPE 00 16K LDPC 01 64K LDPC 10~11 Reserved

DP_COD: This 4-bit field indicates the code rate used by the associatedDP. The code rate is signaled according to the below table 15.

TABLE 15 Value Code rate 0000 5/15 0001 6/15 0010 7/15 0011 8/15 01009/15 0101 10/15  0110 11/15  0111 12/15  1000 13/15  1001~1111 Reserved

DP_MOD: This 4-bit field indicates the modulation used by the associatedDP. The modulation is signaled according to the below table 16.

TABLE 16 Value Modulation 0000 QPSK 0001 QAM-16 0010 NUQ-64 0011 NUQ-2560100 NUQ-1024 0101 NUC-16 0110 NUC-64 0111 NUC-256 1000 NUC-10241001~1111 reserved

DP_SSD_FLAG: This 1 -bit field indicates whether the SSD mode is used inthe associated DP. If this field is set to value ‘1’, SSD is used. Ifthis field is set to value‘0’, SSD is not used.

The following field appears only if PHY_PROFILE is equal to ‘010’, whichindicates the advanced profile.

DP_MIMO: This 3-bit field indicates which type of MIMO encoding processis applied to the associated DP. The type of MIMO encoding process issignaled according to the table 17.

TABLE 17 Value MIMO encoding 000 FR-SM 001 FRFD-SM 010~111 reserved

DP_TI_TYPE: This 1-bit field indicates the type of time-interleaving. Avalue of ‘0’ indicates that one TI group corresponds to one frame andcontains one or more TI-blocks. A value of ‘1’ indicates that one TIgroup is carried in more than one frame and contains only one TI-block.

DP_TI_LENGTH: The use of this 2-bit field (the allowed values are only1,2,4, 8) is determined by the values set within the DP_TI_TYPE field asfollows:

If the DP_TI_TYPE is set to the ‘value’ P, this field indicates PI, thenumber of the frames to which each TI group is mapped, and there is oneTI-block per TI group (NTI-1). The allowed PI values with 2-bit fieldare defined in the below table 18.

If the DP_TI_TYPE is set to the value ‘1’, this field indicates thenumber of TI-blocks NTI per TI group, and there is one TI group perframe (PI=1). The allowed PI values with 2-bit field are defined in thebelow table 18.

TABLE 18 Value Modulation 0000 QPSK 0001 QAM-16 0010 NUQ-64 0011 NUQ-2560100 NUQ-1024 0101 NUC-16 0110 NUC-64 0111 NUC-256 1000 NUC-10241001~1111 reserved

DP_FRAME_INTERVAL: This 2-bit field indicates the frame interval (IJUMP)within the frame-group for the associated DP and the allowed values are1, 2, 4, 8 (the corresponding 2-bit field is ‘00’, ‘01’, ‘10’, or ‘11’,respectively). For DPs that do not appear every frame of theframe-group, the value of this field is equal to the interval betweensuccessive frames. For example, if a DP appears on the frames 1, 5, 9,13, etc., this field is set to ‘4’. For DPs that appear in every frame,this field is set to ‘2’.

DP_TI_BYPASS: This is 1-bit field determines the availability of timeinterleaver 5050. If time interleaving is not used for a DP, it is setto ‘1’. Whereas if time interleaving is used it is set to ‘0’.

DP_FIRST_FRAME_IDX: This 5-bit field indicates the index of the firstframe of the super-frame in which the current DP occurs. The value ofDP_FIRST_FRAME_IDX ranges from 0 to 31

DP_NUM_BLOCK_MAX: This 10-bit field indicates the maximum value ofDP_NUM_BLOCKS for this DP. The value of this field has the same range asDP_NUM_BLOCKS.

DP_PAYLOAD_TYPE: This 2-bit field indicates the type of the payload datacarried by the given DP. DP_PAYLOAD_TYPE is signaled according to thebelow table 19.

TABLE 19 Value Modulation 0000 QPSK 0001 QAM-16 0010 NUQ-64 0011 NUQ-2560100 NUQ-1024 0101 NUC-16 0110 NUC-64 0111 NUC-256 1000 NUC-10241001~1111 reserved

DP_INBAND_MODE: This 2-bit field indicates whether the current DPcarries in-band signaling information. The in-band signaling type issignaled according to the below table 20.

TABLE 20 Value In-band mode 00 In-band signaling is not carried. 01INBAND-PLS is carried only 10 INBAND-ISSY is carried only 11 INBAND-PLSand INBAND-ISSY are carried

DP_PROTOCOL_TYPE: This 2-bit field indicates the protocol type of thepayload carried by the given DP. It is signaled according to the belowtable 21 when input payload types are selected.

TABLE 21 Value In-band mode 00 In-band signaling is not carried. 01INBAND-PLS is carried only 10 INBAND-ISSY is carried only 11 INBAND-PLSand INBAND-ISSY are carried

DP_CRC_MODE: This 2-bit field indicates whether CRC encoding is used inthe Input Formatting block. The CRC mode is signaled according to thebelow table 22.

TABLE 22 Value In-band mode 00 In-band signaling is not carried. 01INBAND-PLS is carried only 10 INBAND-ISSY is carried only 11 INBAND-PLSand INBAND-ISSY are carried

DNP_MODE: This 2-bit field indicates the null-packet deletion mode usedby the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). DNP_MODEis signaled according to the below table 23. If DP_PAYLOAD_TYPE is notTS (‘00’), DNP _MODE is set to the value ‘00’.

TABLE 23 Value In-band mode 00 In-band signaling is not carried. 01INBAND-PLS is carried only 10 INBAND-ISSY is carried only 11 INBAND-PLSand INBAND-ISSY are carried

ISSY_MODE: This 2-bit field indicates the ISSY mode used by theassociated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). The lSSY_MODE issignaled according to the below table 24 If DP PAYLOAD TYPE is not TS(‘00’), ISSY_MODE is set to the value ‘00’.

TABLE 24 Value ISSY mode 00 Not used 01 ISSY-UP 10 ISSY-BBF 11 reserved

HC_MODE_TS; This 2-bit field indicates the TS header compression modeused by the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). TheHC_MODE_TS is signaled according to the below table 25.

TABLE 25 Value Header compression mode 00 HC_MODE_TS 1 01 HC_MODE_TS 210 HC_MODE_TS 3 11 HC_MODE_TS 4

HC_MODE_IP: This 2-bit field indicates the IP header compression modewhen DP_PAYLOAD_TYPE is set to IP (‘01’). The HC_MODE_IP is signaledaccording to the below table 26.

TABLE 26 Value Header compression mode 00 No compression 01 HC_MODE_IP 110~11 reserved

PID : This 13-bit field indicates the PID number for TS headercompression when DP_PAYLOAD_TYPE is set to TS (‘00’) and HC_MODE_TS isset to ‘01’ or ‘10’.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if FIC_FLAG is equal to ‘’:

FIC_VERSION; This 8-bit field indicates the version number of the FIC.

FIC_LENGTH_BYTE: This 13-bit field indicates the length, in bytes, ofthe FIC.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if AUX FLAG is equal to ‘1’:

NUM_AUX: This 4-bit field indicates the number of auxiliary streams.Zero means no auxiliary streams are used.

AUX_CONFIG_RFU: This 8-bit field is reserved for future use.

AUX_STREAM_TYPE: This 4-bit is reserved for future use for indicatingthe type of the current auxiliary stream.

AUX_PRIVATE_CONFIG: This 28-bit field is reserved for future use forsignaling auxiliary streams.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 15 Illustrates PLS2-DYN data of the PLS2 data. The values of thePLS2-DYN data may change during the duration of one frame-group, whilethe size of fields remains constant.

The details of fields of the PLS2-DYN data are as follows:

FRAME_INDEX: This 5-bit field indicates the frame index of the currentframe within the super-frame. The index of the first frame of thesuper-frame is set to ‘0’.

PLS_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration will change. The nextsuper-frame with changes in the configuration is indicated by the valuesignaled within this field. If this field is set to the value ‘0000’, itmeans that no scheduled change is foreseen: e.g., value ‘1’ indicatesthat there is a change in the next super-frame.

FIC_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration (i.e., the contents of theFIC) will change. The next super-frame with changes in the configurationis indicated by the value signaled within this field. If this field isset to the value ‘0000’, it means that no scheduled change is foreseen:e.g. value ‘0001’ indicates that there is a change in the nextsuper-frame.

RESERVED: This 16-bit field is reserved for future use.

The following fields appear in the loop over NUM_DP, which describe theparameters associated with the DP carried in the current frame.

DP_ID: This 6-bit field indicates uniquely the DP within a PHY profile.

DP_START: This 15-bit (or 13-bit) field indicates the start position ofthe first of the DPs using the DPU addressing scheme. The DP_START fieldhas differing length according to the PHY profile and FFT size as shownin the below table 27.

TABLE 27 Value Header compression mode 00 No compression 01 HC_MODE_IP 110~11 reserved

DP_NUM_BLOCK: This 10-bit field indicates the number of FEC blocks inthe current TI group for the current DP. The value of DP_NUM_BLOCKranges from 0 to 1023

RESERVED: This 8-bit field is reserved for future use.

The following fields indicate the FIC parameters associated with theEAC.

EAC_FLAG: This 1-bit field indicates the existence of the EAC in thecurrent frame. This bit is the same value as the EAC FLAG in thepreamble.

EAS_WAKE_UP_VERSION_NUM: This 8-bit field indicates the version numberof a wake-up indication.

If the EAC_FLAG field is equal to ‘1’, the following 12 bits areallocated for EAC_LENGTH_BYTE field. If the EAC_FLAG field is equal to‘0’, the following 12 bits are allocated for EAC_COUNTER.

EAC_LENGTH_BYTE: This 12-bit field indicates the length, in byte, of theEAC.

EAC_COUNTER: This 12-bit field indicates the number of the frames beforethe frame where the EAC arrives.

The following field appears only if the AUX_FLAG field is equal to ‘1’:

AUX_PRIVATE_DYN: This 48-bit field is reserved for future use forsignaling auxiliary streams. The meaning of this field depends on thevalue of AUX STREAM TYPE in the configurable PLS2-STAT.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS2.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

As above mentioned, the PLS, EAC, FIC, DPs, auxiliary streams and dummycells are mapped into the active carriers of the OFDM symbols in theframe. The PLS1 and PLS2 are first mapped into one or more FSS(s). Afterthat, EAC cells, if any, are mapped immediately following the PLS field,followed next by FIC cells, if any. The DPs are mapped next after thePLS or EAC, FIC, if any. Type 1 DPs follows first, and Type 2 DPs next.The details of a type of the DP will be described later. In some case,DPs may carry some special data for EAS or service signaling data. Theauxiliary stream or streams, if any, follow the DPs, which in turn arefollowed by dummy cells. Mapping them all together in the abovementioned order, i.e. PLS, EAC, FIC, DPs, auxiliary streams and dummydata cells exactly fill the cell capacity in the frame.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

PLS cells are mapped to the active carriers of FSS(s). Depending on thenumber of cells occupied by PLS, one or more symbols are designated asFSS(s), and the number of FSS(s) NFSS is signaled by NUM_FSS in PLS1.The FSS is a special symbol for carrying PLS cells. Since robustness andlatency are critical issues in the PLS, the FSS(s) has higher density ofpilots allowing fast synchronization and frequency-only interpolationwithin the FSS.

PLS cells are mapped to active carriers of the NFSS FSS(s) in a top-downmanner as shown in an example in FIG. 17. The PLS1 cells are mappedfirst from the first cell of the first FSS in an increasing order of thecell index. The PLS2 cells follow immediately after the last cell of thePLS1 and mapping continues downward until the last cell index of thefirst FSS. If the total number of required PLS cells exceeds the numberof active carriers of one FSS, mapping proceeds to the next FSS andcontinues in exactly the same manner as the first FSS.

After PLS mapping is completed, DPs are carried next. If EAC, FIC orboth are present in the current frame, they are placed between PLS and“normal” DPs.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

EAC is a dedicated channel for carrying EAS messages and links to theDPs for EAS. EAS support is provided but EAC itself may or may not bepresent in every frame. EAC, if any, is mapped immediately after thePLS2 cells. EAC is not preceded by any of the FIC, DPs, auxiliarystreams or dummy cells other than the PLS cells. The procedure ofmapping the EAC cells is exactly the same as that of the PLS.

The EAC cells are mapped from the next cell of the PLS2 in increasingorder of the cell index as shown in the example in FIG. 18. Depending onthe EAS message size, EAC cells may occupy a few symbols, as shown inFIG. 18.

EAC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required EAC cells exceeds the number of remainingactive carriers of the last FSS mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol, which has more activecarriers than a FSS.

After EAC mapping is completed, the FIC is carried next, if any exists.If FIC is not transmitted (as signaled in the PLS2 field), DPs followimmediately after the last cell of the EAC.

FIG. 19 illustrates FIC mapping: according to an embodiment of thepresent invention.

shows an example mapping of FIC cell without EAC and (b) shows anexample mapping of FIC cell with EAC.

FIC is a dedicated channel for carrying cross-layer information toenable fast service acquisition and channel scanning. This informationprimarily includes channel binding information between DPs and theservices of each broadcaster. For fast scan, a receiver can decode FICand obtain information such as broadcaster ID, number of services, andBASE_DP_ID. For fast service acquisition, in addition to FIC, base DPcan be decoded using BASE_DP_ID. Other than the content it carries, abase DP is encoded and mapped to a frame in exactly the same way as anormal DP. Therefore, no additional description is required for a baseDP. The FIC data is generated and consumed in the Management Layer. Thecontent of FIC data is as described in the Management Layerspecification.

The FIC data is optional and the use of FIC is signaled by the FIC_FLAGparameter in the static part of the PLS2. If FIC is used, FIC_FLAG isset to ‘1’ and the signaling field for FIC is defined in the static partof PLS2, Signaled in this Held are FIC_VERSION, and FIC_LENGTH_BYTE. FICuses the same modulation, coding and time interleaving parameters asPLS2. FIC shares the same signaling parameters such as PLS2 MOD and PLS2FEC. FIC data, if any, is mapped immediately after PLS2 or EAC if any.FIC is not preceded by any normal DPs, auxiliary streams or dummy cells.The method of mapping FIC cells is exactly the same as that of EAC whichis again the same as PLS.

Without EAC after PLS, FIC cells are mapped from the next cell of thePLS2 in an increasing order of the cell index as shown in an example in(a). Depending on the FIC data size, FIC cells may be mapped over a fewsymbols, as shown in (b).

FIC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required FIC cells exceeds the number of remainingactive carriers of the last FSS, mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol which has more activecarriers than a FSS.

If EAS messages are transmitted in the current frame, EAC precedes FIC,and FIC cells are mapped from the next cell of the EAC in an increasingorder of the cell index as shown in (b).

After FIC mapping is completed, one or more DPs are mapped, followed byauxiliary streams, if any, and dummy cells.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

shows type 1 DP and (b) shows type 2 DP.

After the preceding channels, i.e., PLS, EAC and FIC, are mapped, cellsof the DPs are mapped. A DP is categorized into one of two typesaccording to mapping method:

Type 1 DP: DP is mapped by TDM

Type 2 DP: DP is mapped by FDM

The type of DP is indicated by DP_TYPE field in the static part of PLS2.FIG. 20 illustrates the mapping orders of Type 1 DPs and Type 2 DPs.Type 1 DPs are first mapped in the increasing order of cell index, andthen after reaching the last cell index, the symbol index is increasedby one. Within the next symbol, the DP continues to be mapped in theincreasing-order of cell index starting from p=0. With a number of DPsmapped together in one frame, each of the Type 1 DPs are grouped intime, similar to TDM multiplexing of DPs.

Type 2 DPs are first mapped in the increasing order of symbol index, andthen after reaching the last OFDM symbol of the frame, the cell indexincreases by one and the symbol index rolls back to the first availablesymbol and then increases from that symbol index. After mapping a numberof DPs together in one frame, each of the Type 2 DPs are grouped infrequency together, similar to EDM multiplexing of DPs.

Type 1 DPs and Type 2 DPs can coexist in a frame if needed with onerestriction; Type 1 DPs always precede Type 2 DPs. The total number ofOFDM cells carrying Type 1 and Type 2 DPs cannot exceed the total numberof OFDM cells available for transmission of DPs;

D_(DP1)+D_(DP2)≤D_(DP)   Math Figure 2

where DDP1 is the number of OFDM cells occupied by Type 1 DPs, DDP2 isthe number of cells occupied by Type 2 DPs. Since PLS, EAC, FIC are allmapped in the same way as Type 1 DP, they all follow “Type 1 mappingrule”. Hence, overall, Type 1 mapping always precedes Type 2 mapping.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

shows an addressing of OFDM cells for mapping type 1 DPs and (b) showsan an addressing of OFDM cells for mapping for type 2 DPs.

Addressing of OFDM cells for mapping Type 1 DPs (0, . . . , DDP1 l) isdefined for the active data cells of Type 1 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 1DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Without EAC and FIC, address 0 refers to the cell immediately followingthe last cell carrying PLS in the last FSS. If EAC is transmitted andFIC is not in the corresponding frame, address 0 refers to the cellimmediately following the last cell carrying EAC. If FIC is transmittedin the corresponding frame, address 0 refers to the cell immediatelyfollowing the last cell carrying FIC. Address 0 for Type 1 DPs can hecalculated considering two different cases as shown in (a). In theexample in (a), PLS, EAC and FIC are assumed to be all transmitted.Extension to the cases where either or both of EAC and FIC are omittedis straightforward. If there are remaining cells in the FSS aftermapping all the cells up to FIC as shown on the left side of (a).

Addressing of OFDM cells for mapping Type 2 DPs (0, . . . , DDP2 1) isdefined for the active data cells of Type 2 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 2DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Three slightly different cases are possible as shown in (b). For thefirst case shown on the left side of (b), cells in the last FSS areavailable for Type 2 DP mapping. For the second case shown in themiddle, FIC occupies cells of a normal symbol, but the number of FICcells on that symbol is not larger than CFSS. The third case, shown onthe right side in (b), is the same as the second case except that thenumber of FIC cells mapped on that symbol exceeds CFSS.

The extension to the ease where Type 1 DP(s) precede Type 2 DP(s) isstraightforward since PLS, EAC and FIC follow the same “Type 1 mappingrule” as the Type 1 DP(s).

A data pipe unit (DPU) is a basic unit for allocating data cells to a DPin a frame.

A DPU is defined as a signaling unit for locating DPs in a frame. A CellMapper 7010 may map the cells produced by the TIs for each of the DPs. ATime interleaver 5050 outputs a series of TI-blocks and each TI-blockcomprises a variable number of XFECBLOCKs which is in turn composed of aset of cells. The number of cells in an XFECBLOCK, Ncells, is dependenton the FECBLOCK size, Nldpc, and the number of transmitted bits perconstellation symbol. A DPU is defined as the greatest common divisor ofall possible values of the number of cells in a XFECBLOCK, Ncells,supported in a given PHY profile. The length of a DPU in cells isdefined as LDPU. Since each PHY profile supports different combinationsof FECBLOCK size and a different number of bits per constellationsymbol, LDPU is defined on a PHY profile basis.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention before bit interleaving. As above mentioned, Data FECencoder may perform the FEC encoding on the input BBF to generateFECBLOCK procedure using outer coding (BCH), and inner coding (LDPC).The illustrated FEC structure corresponds to the FECBLOCK. Also, theFECBLOCK and the FEC structure have same value corresponding to a lengthof LDPC codeword.

The BCH encoding is applied to each BBF (Kbch bits), and then LDPCencoding is applied to BCH-encoded BBF (Kldpc bits=Nbch bits) asillustrated in FIG. 22.

The value of Nldpc is either 64800 bits (long FECBLOCK) or 16200 bits(short FECBLOCK).

The below table 28 and table 29 show FEC encoding parameters for a longFECBLOCK and a short FECBLOCK, respectively.

TABLE 28 BCH error LDPC correction Rate N_(ldpc) K_(ldpc) K_(bch)capability N_(bch) − K_(bch) 5/15 64800 21600 21408 12 192 6/15 2592025728 7/15 30240 30048 8/15 34560 34368 9/15 38880 38688 10/15  4320043008 11/15  47520 47328 12/15  51840 51648 13/15  56160 55968

TABLE 29 BCH error LDPC correction Rate N_(ldpc) K_(ldpc) K_(bch)capability N_(bch) − K_(bch) 5/15 64800 21600 21408 12 192 6/15 2592025728 7/15 30240 30048 8/15 34560 34368 9/15 38880 38688 10/15  4320043008 11/15  47520 47328 12/15  51840 51648 13/15  56160 55968

The details of operations of the BCH encoding and LDPC encoding are asfollows:

A 12-error correcting BCH code is used for outer encoding of the BBF.The BCH generator polynomial for short FECBLOCK and long FECBLOCK areobtained by multiplying together all polynomials.

LDPC code is used to encode the output of the outer BCH encoding. Togenerate a completed Bldpe (FECBLOCK), Pldpc (parity bits) is encodedsystematically from each Ildpc (BCH-encoded BBF), and appended to Ildpc.The completed Bldpc (FECBLOCK) are expressed as follow Math Figure.

B_(ldpc)=[I_(ldpc)P_(ldpc)]=[i₀, i₁, . . . , i_(k) _(ldpc) ⁻¹,p₀,p₁, . .. ,p_(N) _(ldpc) _(−k) _(ldpc) _(−1])  Math Figure 3

The parameters for long FECBLOCK and short FECBLOCK are given in theabove table 28 and 29, respectively,

The detailed procedure to calculate Nldpc−Kldpc parity bits for longFECBLOCK, is as follows:

1) Initialize the parity bits,

p₀=p₁=p₂=. . . =p_(N) _(ldpc) _(−K) _(ldpc) ⁻¹=0   Math Figure 4

2) Accumulate the first information bit-i0, at parity bit addressesspecified in the first row of an addresses of parity check matrix. Thedetails of addresses of parity check matrix will be described later. Forexample, for rate 13/15:

p₉₈₃=p₉₈₃⊕i₀

p₄₈₃₇=p₄₈₃₇⊕i₀

p₆₁₃₈=p₆₁₃₈⊕i₀

p_(692l)=p₆₉₂₁⊕i₀

p₁₅₁₂=p₁₅₁₂⊕i₀

p₈₄₉₆=p₈₄₉₆⊕i₀

p₂₈₁₅=p₂₈₁₅ ⊕i₀

p₄₉₈₉=p₄₉₈₉⊕i₀

p₆₄₅₈=p₆₄₅₈⊕i₀

p₆₉₇₄=p₆₉₇₄⊕i₀

p₈₂₆₀=p₈₂₆₀ ⊕i₀  Math Figure 5

3) For the next 359 information bits, is, s=1, 2,. . . , 359 accumulateis at parity bit addresses using following Math Figure.

{x+(s mod 360)×Q_(ldpc)}mod (N_(ldpc)−K_(ldpc))   Math Figure 6

where x denotes the address of the parity bit accumulator correspondingto the first bit i0, and Qldpc is a code rate dependent constantspecified in the addresses of parity check matrix. Continuing with theexample, Qldpc=24 for rate 13/15, so for information bit il, thefollowing operations are performed:

p₁₀₀₇=p₁₀₀₇⊕i₁

p₄₈₆₁=p₄₈₆₁⊕i₁

p₆₁₆₂=p₆₁₆₂⊕i₁

p₆₉₄₅=p₆₉₄₅⊕i₁

p₁₅₉₆=p₁₅₉₆⊕i₁

p₈₅₂₀=p₈₅₂₀⊕i₁

p₂₈₃₉=p₂₈₃₉ ⊕i₁

p₅₀₁₃=p₅₀₁₃⊕i₁

p₆₄₈₂=p₆₄₈₂⊕i₁

p₆₉₉₈=p₆₉₉₈⊕i₁

p₈₂₃₄=p₈₂₃₄ ⊕i₁  Math Figure 7

4) For the 361st information bit i360, the addresses of the parity bitaccumulators are given in the second row of the addresses of paritycheck matrix. In a similar manner the addresses of the parity bitaccumulators for the following 359 information bits is, s=361, 362, . .. , 719 are obtained using the Math Figure 6, where x denotes theaddress of the parity bit accumulator corresponding to the informationbit i360, i.e., the entries in the second row of the addresses of paritycheck matrix.

5) In a similar manner, for every group of 360 new information bits, anew row from addresses of parity check matrixes used to find theaddresses of the parity bit accumulators.

After all of the information bits are exhausted, the final parity bitsare obtained as follows:

6) Sequentially perform the following operations starting with i=1

p _(i) =p _(i) ⊕p _(i−1) , i=1,2, . . . , N _(ldpc) −K _(ldpc)−1   MathFigure 8

where final content of pi, i=0,1,. . . Nldpc−Kldpc−1 is equal to theparity bit pi.

TABLE 30 Code Rate Q_(ldpc) 5/15 120 6/15 108 7/15 96 8/15 84 9/15 7210/15  60 11/15  48 12/15  36 13/15  24

This LDPC encoding procedure for a short FECBLOCK is in accordance witht LDPC encoding procedure for the long FECBLOCK, except replacing thetable 30 with table 31, and replacing the addresses of parity checkmatrix for the long FECBLOCK with the addresses of parity check matrixfor the short FECBLOCK.

TABLE 31 Code Rate Q_(ldpc) 5/15 30 6/15 27 7/15 24 8/15 21 9/15 1810/15  15 11/15  12 12/15  9 13/15  6

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

The outputs of the LDPC encoder are bit-interleaver , which consists ofparity interleaving followed by Quasi-Cyclic Block (QCB) interleavingand inner-group interleaving.

shows Quasi-Cyclic Block (QCB) interleaving and (b) shows inner-groupinterleaving.

The FECBLOCK may be parity interleaver. At the output of the parityinterleaving, the LDPC codeword consists of 180 adjacent QC blocks in along FECBLOCK and 45 adjacent QC blocks in a short FECBLOCK. Each QCblock in either a long or short FECBLOCK consists of 360 bits. Theparity interleaver LDPC codeword is interleaver by QCB interleaving. Theunit of QCB interleaving is a QC block. The QC blocks at the output ofparity interleaving are permutated by QCB interleaving as illustrated inFIG. 23, where Ncells=64800/ηmod or 16200/ηmod according to the FECBLOCKlength. The QCB interleaving pattern is unique to each combination ofmodulation type and LDPC code rate.

After QCB interleaving, inner-group interleaving is performed accordingto modulation type and order (ηmod) which is defined in the below table32. The number of QC blocks for one inner-group, NQCB_IG, is alsodefined.

TABLE 32 Modulation type ηmod N_(QCB) _(—) _(IG) QAM-16 4 2 NUC-16 4 4NUQ-64 6 3 NUC-64 6 6 NUQ-256 8 4 NUC-256 8 8 NUQ-1024 10 5 NUC-1024 1010

The inner-group Interleaving process is performed with NQCB_IG QC blocksof the QCB interleaving output. Inner-group interleaving has a processof writing and reading the bits of the inner-group using 360 columns andNQCB_IG rows. In the write operation, the bits from the QCB interleavingoutput are written row-wise. The read operation is performed column-wiseto read out m bits from each row, where m is equal to 1 for NUC and 2for NUQ.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

FIG. 24 shows a cell-word demultiplexing for 8 and 12 bpcu MIMO and (b)shows a cell-word demultiplexing for 10 bpcu MIMO.

Each cell word (c0,1, c1,1, . . . , cηmod-1,1) of the bit interleavingoutput is demultiplexed into (d1,0,m, d1,1,m . . . , d1,3,m) and(d2,0,m, d2,1,m . . . , d2,5,m) as shown in (a), which describes thecell-word demultiplexing process for one XFECBLOCK.

For the 10 bpcu MIMO case using different types of NUQ for MIMOencoding, the Bit Interleavcr for NUQ-1024 is re-used. Each cell word(c0,1, c1,1, . . . ,c9,1) of the Bit Interleaver output is demultiplexedinto (d1,0,m, d1,1,m . . . , d1,3,m) and (d2,0,m, d2,1,m . . . ,d2,5,m), as shown in (b).

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

to (c) show examples of TI mode.

The time interleaver operates at the DP level. The parameters of timeinterleaving (TI) may be set differently for each DP.

The following parameters, which appear in pary of the PLS2-STAT data,configure the TI;

DP_TI_TYPE (allowed values: 0 or 1): Represents the TI mode; ‘0’indicates the mode with multiple TI blocks (more than one TI block) perTI group. In this case, one TI group is directly mapped to one frame (nointer-frame interleaving). ‘1’ indicates the mode with only one TI blockper TI group. In this case, the TI block may be spread over more thanone frame (inter-frame interleaving).

DP_TI_LENGTH: If DP_TI_TYPE=‘0’, this parameter is the number of TIblocks NTI per TI group. For DP_TI_TYPE=‘1’, this parameter is thenumber of frames PI spread from one TI group.

DP_NUM_BLOCK_MAX (allowed values: 0 to 1023): Represents the maximumnumber of XFECBLOCKs per TI group.

DP_FRAME_INTERVAL (allowed values: 1, 2, 4, 8): Represents the number ofthe frames IJUMP between two successive frames carrying the same DP of agiven PHY profile.

DP_TI_BYPASS (allowed values: 0 or 1): If time interleaving is not usedfor a DP, this parameter is set to ‘1’0. It is set to ‘0’ if timeinterleaving is used.

Additionally, the parameter DP_NUM_BLOCK from the PLS2-DYN data is usedto represent the number of XFECBLOCKs carried by one TI group of the DP.

When time interleaving is not used for a DP, the following TI group,time interleaving operation, and TI mode are not considered. However,the Delay Compensation block for the dynamic configuration informationfrom the scheduler will still be required. In each DP, the XFECBLOCKsreceived from the SSD/MIMO encoding are grouped into TI groups. That is,each TI group is a set of an integer number of XFECBLOCKs and willcontain a dynamically variable number of XFECBLOCKs. The number ofXFECBLOCKs in the TI group of index n is denoted by NxBLOCK_Group(n) andis signaled as DP_NUM_BLOCK in the PLS2-DYN data. Note thatNxBLOCK_Group(n) may vary from the minimum value of 0 to the maximumvalue NxBLOCK_Group MAX (corresponding to DP_NUM_BLOCK_MAX) of which thelargest value is 1023.

Each TI group is either mapped directly onto one frame or spread over PIframes. Each TI group is also divided into more than one TI blocks(NTI),where each TI block corresponds to one usage of time interleaver memory.The TI blocks within the TI group may contain slightly different numbersof XFECBLOCKs. If the TI group is divided into multiple TI blocks, it isdirectly mapped to only one frame. There are three options for timeinterleaving (except the extra option of skipping the time interleaving)as shown in the below table 33.

TABLE 33 Modes Descriptions Op- Each TI group contains one TI block andis mapped directly to tion-1 one frame as shown in (a). This option issignaled in the PLS2-STAT by DP_TI_TYPE = ‘0’ and DP_TI_LENGTH =‘1’(N_(TI) = 1). Op- Each TI group contains one TI block and is mappedto more than tion-2 one frame. (b) shows an example, where one TI groupis mapped to two frames, i.e., DP_TI_LENGTH = ‘2’ (P_(I) = 2) andDP_FRAME_INTERVAL (I_(JUMP) = 2). This provides greater time diversityfor low data-rate services. This option is signaled in the PLS2-STAT byDP_TI_TYPE = ‘1’. Op- Each TI group is divided into multiple TI blocksand is mapped tion-3 directly to one frame as shown in (c). Each TIblock may use full TI memory, so as to provide the maximum bit-rate fora DP. This option is signaled in the PLS2-STAT signaling by DP_TI_TYPE =‘0’ and DP_TI_LENGTH = N_(TI), while P_(I) = 1.

In each DP, the TI memory stores the input XFECBLOCKs (output XFECBLOCKsfrom the SSD/MIMO encoding block). Assume that input XFECBLOCKs aredefined as

(d _(n,s,0,0) , d _(n,s,0,1) , . . . ,d _(n,s,O,N) _(cells)⁻¹,d_(n,s,1,N) _(cells) ⁻¹ , . . . , ,d _(n,s,1,N) _(cells) ₁ , . . . ,d_(n,s,N) _(xBLOCK,TI) _((n,s)−1,0), . . . ,d_(n,s,N) _(xBLOCK_TI)_((n,s)−1,N) _(cells) ₁),

where d _(n,s,r,q) is the qth cell of the rth XFECBLOCK in the sth TIblock of the nth TI group and represents the outputs of SSD and MIMOencodings as follows

$d_{n,s,r,q} = \left\{ {\begin{matrix}{f_{n,s,r,q},} & {{the}\mspace{14mu} {output}\mspace{14mu} {of}\mspace{14mu} {SSD}\mspace{14mu} \ldots \mspace{14mu} {encoding}} \\{g_{n,s,r,q},} & {{the}\mspace{14mu} {output}\mspace{14mu} {of}\mspace{14mu} {MIMO}\mspace{14mu} {encoding}}\end{matrix}.} \right.$

In addition, assume that output XFECBLOCKs from the time interleaver5050 are defined as (h_(n,s,0)h_(n,s,1), . . . , h_(n,s,j), . . . ,h_(n,s,N) _(xBLOCKn) _((n,s)×N) _(cells) ⁻¹) where h_(n,s,l) is the ithoutput cell (for i=0, . . . , N_(xBL0CK) _(_) _(TI)(n,s)×N_(cells)−1) inthe sth TI block of the nth TI group.

Typically, the time interleaver will also act as a buffer for DP dataprior to the process of frame building. This is achieved by means of twomemory banks for each DP. The first TI-block is written to thefirst-bank. The second TI-block is written to the second bank while thefirst bank is being read from and so on.

The TI is a twisted row-column block interleaver. For the sth TI blockof the nth TI group, the number of rows N, of a TI memory is equal tothe number of cells N_(cells), i.e., N_(r)=N_(cells) while the number ofcolumns N_(c) is equal to the number N_(sBLOCK) ₁₃ _(TI)(n,s).

FIG. 26 illustrates the basic operation of a twisted row-column blockinterleaver according to an embodiment of the present invention.

FIG. 26 (a) shows a writing operation in the time interleaver and FIG.26(b) shows a reading operation in the time interleaver. The firstXFECBLOCK is written column-wise into the first column of the TI memory,and the second XFECBLOCK is written into the next column, and so on asshown in (a). Then, in the interleaving array, cells are read outdiagonal-wise. During diagonal-wise reading from the first row(rightwards along the row beginning with the left-most column) to thelast row, N_(r) cells are read out as shown in (b). In detail, assumingz_(n,r,i)(i=0, . . . , N,N_(c)) as the TI memory cell position to beread sequentially the reading process in such an interleaving array isperformed by calculating the row index R_(n,s,l) the column indexC_(n,s,l), and the associated twisting parameter as follows expression.

$\begin{matrix}{{{GENERATE}\left( {R_{n,s,l},C_{n,s,l}} \right)} = \left\{ {{R_{n,s,l} = {{mod}\left( {l,N_{r}} \right)}},{T_{n,s,l} = {{mod}\left( {{S_{shift} \times R_{n,s,l}},N_{c}} \right)}},{C_{n,s,l} = {{mod}\left( {{T_{n,s,l} + \left\lfloor \frac{i}{N_{r}} \right\rfloor},N_{c}} \right)}}} \right\}} & {{Math}\mspace{14mu} {{FIG}.\mspace{14mu} 9}}\end{matrix}$

where S_(shift) is a common shift value for the diagonal-wise readingprocess regardless of N_(xBLOCK) _(_) _(TI)(n,s), and it is determinedby N_(xBLOCK) _(_) _(TI) _(_) _(MAX) given in the PLS2-STAT as followsexpression.

                                    Math  FIG.  10${for}\left\{ {\begin{matrix}{{N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MA}\; X}^{\prime} = {N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MA}\; X} + 1}},} & {{{if}\mspace{14mu} N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MA}\; X}{mod}\; 2} = 0} \\{{N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MA}\; X}^{\prime} = N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MA}\; X}},} & {{{if}\mspace{14mu} N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MA}\; X}{mod}\; 2} = 1}\end{matrix},\mspace{20mu} {S_{shift} = \frac{N_{{xBLOCK}\; \_ \; {TI}\; \_ \; {MA}\; X}^{\prime} - 1}{2}}} \right.$

As a result, the cell positions to be read are calculated by acoordinate as z_(n,s,l)=N,C_(n,s,l)+R_(n,s,l).

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another embodiment of the present invention.

More specifically, FIG. 27 illustrates the interleaving array in the TImemory for each TI group, including virtual XFECBLOCKs whenN_(xBLOCK TI) (0,0)−3, N_(xBLOCK) _(_) _(TI)(1,0)−6, N_(xBLOCK) _(_)_(TI)(2,0)=5.

The variable number N_(xBLOCK) _(_) _(TI)(n,s)=N, will be less than orequal to N_(xBLOCK) _(_) _(TI) _(_) _(MAX). Thus, in order to achieve asingle-memory deinterleaving at the receiver side, regardless ofN_(xBLOCK) _(_) _(TI)(n,s), the interleaving array for use in a twistedrow-column block interleaver is set to the size ofN_(r)×N_(c)=N_(cells)×N_(xBLOCK) _(_) _(TI) _(_) _(MAX) by inserting thevirtual XFECBLOCKs into the TI memory and the reading process isaccomplished as follow expression.

Math FIG. 11 p = 0; for i = 0; i < N_(cells)N′_(xBLOCK)_TI_MAX; i = i +1 {GENERATE(R_(n,s,i), C_(n,s,i)); V_(i) = N_(r)C_(n,s,j) + R_(n,s,j) if V_(i) < N_(cells)N_(xBLOCK)_TI(n,s)  {   Z_(n,s,p) = V_(i); p = p +1;   } }

The number of TI groups is set to 3. The option of time interleaver issignaled in the PLS2-STAT data by DP_TI_TYPE=‘0’, DP_FRAME_INTERVAL=‘1’,and DP_TI_LENGTH=‘1’, i.e.,NTI=1, IJUMP=1, and PI=1. The number ofXFECBLOCKs, each of which has Ncells=30 cells, per TI group is signaledin the PLS2-DYN data by NxBLOCK_TI(0,0)=3, NxBLOCK_TI(1,0)=6, andNxBLOCK_TI(2,0)=5, respectively. The maximum number of XFECBLOCK issignaled in the PLS2-STAT data by NxBLOCK_Group_MAX, which leads to.

FIG. 28 illustrates a diagonal-wise reading pattern of a twistedrow-column block interleaver according to an embodiment of the presentinvention.

More specifically FIG. 28 shows a diagonal-wise reading pattern fromeach interleaving array with parameters of N_(xBLOCK) _(_) _(TI) _(_)_(MAX)=7 and Sshift=(7−1)/2=3. Note that in the reading process shown aspseudocode above, if V_(i)≥N_(cells)N_(xBLOCK) _(_) _(TI)(n,s), thevalue of Vi is skipped and the next calculated value of Vi is used.

FIG. 29 illustrates interlaved XFECBLOCKs from each interleaving arrayaccording to an embodiment of the present invention.

FIG. 29 illustrates the interleaver XFECBLOCKs from each interleavingarray with parameters of N_(xBLOCK) _(_) _(TI) _(_) _(MAX)=7 andSshift=3.

A description will be given of a method by which a broadcast signaltransmitter protects PLS data by encoding the same according to anembodiment of the present invention. The PLS provides the receiver witha means to access physical layer DPs. The PLS data consists of PLS1 dataand PLS2 data.

PLS1 data provides basic transmission parameters including parametersrequired to enable the reception and decoding of the PLS2. PLS1 fieldsremain unchanged for the entire duration of one frame-group.

The PLS2 contains parameters that provide sufficient information for thereceiver to decode the desired DP. The PLS2 signaling further consistsof two types of parameters, PLS2-STAT and PLS2-DYN. The PLS2-STATparameters are the same within a frame-group, while the PLS2-DYNparameters provide information that is specific for the current frame.The values of the PLS2-DYN parameters may change during the duration ofone frame-group, while the size of fields remains constant.

The PLS1 and the static part of the PLS2 can be changed only on theborder of two super-frames. In the in-band signaling, there is a counterindicating the next super-frame with changes in PLS1 or the static partof the PLS2 parameters. The receiver can locate the change boundary bychecking the new PLS parameters from the FSS(s) in the first frame ofthe announced super-frame, where the indicated change applies.

FIG. 30 illustrates a preamble insertion block according to anembodiment of the present invention.

FIG. 30 shows another embodiment of the preamble insertion block 8050described above. As shown in FIG. 30, the preamble insertion blockaccording to an embodiment of the present invention may include a ReedMuller encoder 17000, a data formatter 17010, a cyclic delay block17020, an interleaver 17030, a DQPSK (Differential Quadrature PhaseShift Keying)/DBPSK (Differential Binary Phase Shift Keying) mapper17040, a scrambler 17050, a carrier allocation block 17060, a carrierallocation table block 17070, an 1FFT block 17080, a scrambled guardinsertion block 17090 and a multiplexing block 17100. Each block may bemodified according to designer or may not be included in the preambleinsertion block. A description will be given of operation of each block.

The Reed Muller encoder 17000 may receive signaling information to betransmitted through a preamble and perform Reed Muller encoding of theinput signaling information. When Reed Muller encoding is performed,signaling performance can be improved over conventional signaling usingan orthogonal sequence.

The data formatter 17010 may receive bits of the Reed-Muller-encodedsignaling information and perform formatting for repeating and arrangingthe input bits.

The DQPSK/DBPSK mapper 17040 may map the formatted signaling informationbits according to DBPSK or DQPSK and output the mapped signalinginformation.

When the DQPSK/DBPSK mapper 17040 maps the formatted signalinginformation bits according to DBPSK, the operation of the cyclic delayblock 17020 may be skipped. The interleaver 17030 may receive theformatted signaling Information bits, frequency-interleave the formattedsignaling information bits and output interleaver data. In this case,the operation of the interleaver 17030 may be omitted according todesigner.

When the DQPSK/DBPSK mapper 17040 maps the formatted signalinginformation bits according to DQPSK, the data formatter 17010 may outputthe formatted signaling information bits to the interleaver 17030through a path I shown in FIG. 30. The cyclic delay block 17020 maycyclic-delay the formatted signaling information bits output from thedata formatter 17010 and then output the delayed signaling informationbits to the interleaver 17030 through a path Q shown in FIG. 30. Whencyclic Q-delay is performed, performance in a frequency selective fadingchannel is improved.

The Interleaver 17030 may perform frequency interleaving on thesignaling information and cyclic Q-delayed signal information, inputthrough the path I and path Q, and output interleaver information. Inthis case, the operation of the interleaver 17030 may be omittedaccording to designer.

The scrambler 17050 may receive the mapped signaling information outputfrom the DQPSK/DBPSK mapper 17040 and multiply the signaling informationby a scrambling sequence.

The carrier allocation block 17060 may arrange the signaling informationprocessed by the scrambler 17050 in a predetermined carrier positionusing position information output from the carrier allocation tableblock 17070.

The LFFT block 17080 may transform carriers output from the carrierallocation block 17060 into an OFDM signal of the time domain.

The scrambled guard insertion block 17090 may insert a scrambled guardinterval into the OFDM signal to generate a preamble. The scrambledguard insertion block 17090 according to an embodiment of the presentinvention may generate the scrambled guard interval by multiplying aguard interval in the form of a cyclic prefix by a scrambling sequence.The scrambled guard interval will be described later in detail, in thepresent invention, the scrambled guard interval can be referred to as ascrambled GI.

The scrambled guard insertion block 17090 may select the scramblingsequence according to whether an EAS message is inserted. The scrambledguard insertion block 17090 may determine whether to insert the EASmessage using EAS flag information that indicates whether the EASmessage is present in the preamble.

The multiplexing block 17100 may multiplex the output of the scrambledguard insertion block 17090 and a signal c(t) output from the guardsequence insertion block 8040 to output an output signal p(t). Theoutput signal p(t) may be output from the preamble insertion block 8050described above.

The preamble insertion block according to an embodiment of the presentinvention can improve signaling performance over conventional signalingusing an orthogonal

sequence by performing Reed Muller encoding and enhance performance in afrequency selective fading channel by performing cyclic Q-delay.

FIG. 31 illustrates preamble structures according to an embodiment ofthe present invention.

The upper side of FIG. 31 shows a structure of the normal preamble andat the bottom of FIG. 31 shows a structure of the robust preamble.

In the structure of the robust preamble according to an embodiment ofthe present invention, the normal preamble is repeated. Specifically, inthe robust preamble structure according to an embodiment of the presentinvention, the normal preamble is repeated twice. The robust preambleaccording to an embodiment of the present invention is designed todetect and decode the preamble symbol under harsh channel conditionslike mobile reception.

The normal preamble shown in the upper side of FIG. 31 may be generatedby the preamble insertion block shown in FIG. 30. The robust preambleshown in the bottom of FIG. 31 may be generated by a preamble insertionblock according to an embodiment of the present invention, shown in FIG.32 or 21, which will be described later.

The normal preamble according to an embodiment of the present inventionmay include a scrambled GI region and an OFDM data region. The scrambledGI region of the preamble according to an embodiment of the presentinvention may be a scrambled cyclic postfix or a scrambled cyclicprefix. The scrambled cyclic postfix may be located after an OFDMsymbol, distinguished from a scrambled prefix and may be generatedthrough the same process as used to generate the scrambled cyclicprefix, which will be described later. The process of generating thescrambled cyclic postfix may be modified according to designer.

The scrambled GI region shown in FIG. 31 may be generated by scramblingsome or all OFDM symbols and used as a guard interval. The scrambled GIand OFDM data of the normal preamble according to an embodiment of thepresent invention may have the same length. In FIG. 31, the scrambled GIand OFDM data have a length of N and the normal preamble has a length of2N. N, which relates to the length of the preamble according to anembodiment of the present invention, may refer to an FFT size.

The preamble according to an embodiment of the present invention iscomposed of 3 signaling fields, namely S1,S2 and S3. Each signalingfield contains 7 signaling bits, and the preamble carries 21 signalingbits in total. Each signaling field is encoded with a first-order ReedMuller (64, 7) code.

The signaling fields according to an embodiment of the present inventionmay include the aforementioned signaling information. The signalingfields will be described in detail later.

The broadcast signal reception apparatus according to an embodiment ofthe present invention can detect a preamble through guard intervalcorrelation using a guard interval in the form of a cyclic prefix evenwhen frequency synchronization cannot be performed.

In addition, the guard interval in the form of a scrambled cyclic prefixaccording to an embodiment of the present invention can be generated bymultiplying (or combining) an OFDM symbol by (or with) a scramblingsequence (or sequence). Furthermore, the guard interval in the form of ascrambled cyclic prefix according to an embodiment of the presentinvention can be generated by scrambling the OFDM symbol and thescrambling sequence. The scrambling sequence according to an embodimentof the present invention can be any type of signal according todesigner.

The method of generating the guard interval in the form of a scrambledcyclic prefix according to an embodiment of the present invention hasthe following advantages.

Firstly, the preamble can be easily detected by discriminating thepreamble from the normal OFDM symbol. The guard interval in the form ofa scrambled cyclic prefix is generated through scrambling using thescrambling sequence, distinguished from the normal OFDM symbol, asdescribed above. In this case, when the broadcast signal receptionapparatus according to an embodiment of the present invention performsguard interval correlation, the preamble can be easily detected since acorrelation peak according to the normal OFDM symbol is not generatedand only a correlation peak according to the preamble is generated.

Secondly, when the guard interval in the form of a scrambled cyclicprefix according to an embodiment of the present invention is used,dangerous delay can be prevented. For example, when, multipathinterference having a delay corresponding to an OFDM symbol period Tuexists, since a correlation value according to multiple paths is presentall the time when the broadcast signal reception apparatus performsguard interval correlation, preamble detection performance may bedeteriorated. However, when the broadcast signal reception apparatusaccording to an embodiment of the present invention performs guardinterval correlation, the preamble can be detected without beingaffected by a correlation value according to multiple paths since only apeak according to the scrambled cyclic prefix is generated, as describedabove.

Finally, influence of continuous wave (CW) interference can beprevented. When a received signal includes CW interference, a DCcomponent according to CW is present all the time during guard intervalcorrelation performed by the broadcast signal reception apparatus andthus signal detection performance and synchronization performance of thebroadcast signal reception apparatus may be deteriorated. However, whenthe guard Interval in the form of a scrambled cyclic prefix according toan embodiment of the present invention is used, the influence of CW canbe prevented since the DC component according to CW is averaged out bythe scrambling sequence.

The robust preamble according to an embodiment of the present inventionhas repeated normal preambles, as shown in the bottom of FIG. 31.Accordingly, the robust preamble may include the scrambled GI region andthe OFDM data region.

The robust preamble is a kind of repetition of the normal preamble, andcarries the same signaling fields S1, S2 and S3 with a differentsignaling scrambler sequence (SSS).

The first half of the robust preamble, shown in the bottom of FIG. 31,is exactly the same as the normal preamble. The second half of therobust preamble is a simple variation of the normal preamble where thedifference arises from the sequence SSS applied in the frequency domain.Accordingly, the second half of the robust preamble includes the sameinformation as that of the normal preamble but may have different datain the frequency domain. In addition, OFDM data B has the same signalingdata as OFDM data A but may have a different output waveform in the timedomain. That is, while inputs of the Reed Muller encoder 17000 forrespectively generating the first half of the robust preamble and thesecond half of the robust preamble are identical, the IFFT block 17080may output different waveforms.

The doubled length of the robust preamble according to an embodiment ofthe present invention improves the detection performance in the timedomain, and the repetition of the signaling fields improves the decodingperformance for the preamble signaling data. The generation process ofthe robust preamble symbol is shown in FIG. 31. The detailed functionalsteps are described in the following description.

The signaling fields will be described in detail with reference to FIGS.37, 38 and 39 and the robust preamble generation process will bedescribed in detail with reference to FIGS. 20 and 21.

The robust preamble according to an embodiment of the present inventioncan be detected even by a normal reception apparatus in an environmenthaving a high SNR (Signal to Noise Ratio) since the robust preambleincludes the normal preamble structure. In an environment having a lowSNR, the robust preamble can be detected using the repeated structure.In FIG. 31(b), the robust preamble has a length of 4N.

When the broadcast signal reception apparatus according to an embodimentof the present invention receives a signal frame including the robustpreamble, the broadcast signal reception apparatus can stably detect thepreamble to decode signaling information even in a Sow SNR situation.

FIGS. 32 and 33 illustrate two methods for generating the robustpreamble according to an embodiment of the present invention. The robustpreamble structure according to an embodiment of the present inventionimproves the detection performance of signals of a broadcast receptionapparatus. The robust preamble may include structure of normal preamble.The robust preamble may additionally include repeated signaling datasame as the normal preamble. In this case, the signals of a broadcasttransmission apparatus according to an embodiment of the presentinvention can design differently repeated signaling data of waveformwhich is included the robust preamble in time domain than signaling dataof waveform which is included the normal preamble in time domain. Arobust preamble insertion block illustrated in FIG. 32 may generate therobust preamble by multiplying signaling information of the preamble bydifferent scrambling sequences in scramblers to output multiple piecesof scrambled signaling information and allocating the multiple pieces ofscrambled signaling information multiplied by the scrambling sequencesto OFDM symbol carriers on the basis of the same carrier allocationtable.

A robust preamble insertion block illustrated in FIG. 33 may generatethe robust preamble by multiplying preamble signaling information by thesame scrambling sequence and allocating the preamble signalinginformation multiplied by the scrambling sequence to OFDM symbolcarriers on the basis of different carrier allocation tables.

Detailed embodiments will now be described with reference to thefigures.

FIG. 32 Illustrates a preamble insertion block according to anembodiment of the present invention.

Specifically, FIG. 32 shows another embodiment of the preamble insertionblock 8050 described above. The preamble insertion block shown in FIG.32 may generate the robust preamble. Referring to FIG. 32, the preambleinsertion block according to an embodiment of the present invention mayinclude a Reed Muller encoder 17000, a data formatter 17010, a cyclicdelay block 17020, an interleaver 17030, a DQPSK (DifferentialQuadrature Phase shift Keying)/DBPSK (Differential Binary Phase ShiftKeying) mapper 17040, a scrambler 17050, a carrier allocation block17060, a carrier allocation table block 17070, an IFFT block 17080, ascrambled guard insertion block 17090 and a multiplexing block 17100.Each block may be modified or may not be included in the preambleinsertion block according to designer. Operations of the blocks may bethe same as those of corresponding blocks shown in FIG. 30. Adescription will be given focusing on a difference between the robustpreamble generation process and the normal preamble generation process.

As described above, the robust preamble is composed of the first half ofthe robust preamble and the second half of the robust preamble and thefirst half of the robust preamble may be the same as the normalpreamble.

Robust preamble generation differs from normal preamble generation onlyby applying the sequence SSS in the frequency domain as described.Consequently, the Reed Muller encoder 17000, the data formatter 17010and the DQPSK/DBPSK mapper block 17040 are shared with the normalpreamble generation.

The first half of the robust preamble may be generated through the sameprocess as used to generate the normal preamble. In FIG. 32, OFDM data Aof the first half of the robust preamble may be generated by scramblingsignalling data input to the Reed Muller encoder 17000 through ascrambler A block 17050-1, a carrier allocation block 17060-1 and anIFFT module, allocating the scrambled data to active carriers andtransforming carriers output from the carrier allocation block 17060-1into an OFDM signal of the time domain.

OFDM data B of the second half of the robust preamble may be generatedby scrambling signalling data input to the Reed Muller encoder 17000through a scrambler B block 17050-2, a carrier allocation block 17060-2and an IFFT module, allocating the scrambled data to active carriers andtransforming carriers output from the carrier allocation block 17060-2into an OFDM signal of the time domain.

The carrier allocation blocks 17060-1 and 17060-2 according to anembodiment of the present invention can allocate the signaling data ofthe first half of the robust preamble and the signaling data of thesecond half of the robust preamble to carriers on the basis of the sameallocation table.

Scrambled guard Insertion modules may respectively scramble OFDM data Aand OFDM data B respectively processed through the IFFT modules togenerate scrambled GI A and scrambled GI B, thereby generating the firsthalf of the robust preamble and the second half of the robust preamble.

FIG. 33 illustrates a preamble insertion block according to anembodiment of the present invention.

Specifically, FIG. 33 shows another embodiment of the preamble insertionblock 8050 described above. The preamble insertion block shown in FIG.32 may generate the robust preamble. Referring to FIG. 33, the preambleinsertion block according to an embodiment of the present invention mayinclude a Reed Muller encoder 17000, a data formatter 17010, a cyclicdelay block 17020, an interleaver 17030, a DQPSK (DifferentialQuadrature Phase shift Keying)/DBPSK (Differential Binary Phase ShiftKeying) mapper 17040, a scrambler 17050, a carrier allocation block17060, a carrier allocation table block 17070, an IFFT block 17080, ascrambled guard insertion block 17090 and a multiplexing block 17100.Each block may be modified or may not be included in the preambleinsertion block according to designer. Operations of the blocks may bethe same as those of corresponding blocks shown in FIG. 30.

A description will be given focusing on a difference between the robustpreamble generation process and the robust preamble generation processof FIG. 32.

The procedure of processing signaling data of the robust preambleaccording to an embodiment of the present invention through the ReedMuller encoder, data formatter, cyclic delay, interleaver, DQPSK/DBPSKmapper and scrambler modules may correspond to the aforementionedprocedure of processing the signaling data of the normal preamblethrough the respective modules.

The signaling data scrambled by the scrambler module may be input to acarrier allocation A module and a carrier allocation B module. Thesignaling information input to the carrier allocation A module and thecarrier allocation B module may be represented as p[n] (n being ainteger greater than 0). Here, p[n] may be represented as p[0] top[N-1](N being the number of carriers to which all signaling informationis allocated (or arranged). The carrier allocation A module and thecarrier allocation B module may allocate (or arrange) the signalinginformation p[n] to carriers on the basis of different carrierallocation tables.

For example, the carrier allocation A module can respectively allocatep[0], p[1] and p[N-l] to the first, second and N-th carriers. Thecarrier allocation B module can respectively allocate p[N-1], p[N-2],p[N-3] and p[0] to the first, second, third and N-th carriers.

The preamble insertion blocks illustrated in FIGS. 32 and 33 cangenerate the first half of the robust preamble and the second half ofthe robust preamble using different scrambling sequences or using thesame scrambling sequence and different carrier allocation schemes.Signal waveforms of the first half and the second half of the robustpreamble generated according to an embodiment of the present inventionmay differ from each other. Accordingly, data offset due to a multipathchannel is not generated even when the same signaling information isrepeatedly transmitted in the time domain.

FIG. 34 is a graph showing a scrambling sequence according to anembodiment of the present invention.

This graph shows a waveform of a binary chirp-like sequence. The binarychirp-like sequence is an embodiment of a signal that can be used as ascrambling sequence of the present invention. The binary chirp-likesequence is a sequence which is quantized such that the real part andimaginary part of each signal value respectively have only ‘1’ and ‘−1’.The binary chirp-like sequence shown in FIG. 34 is composed of aplurality of square waves having different periods and a sequence periodis 1024 according to an embodiment.

The binary chirp-like sequence has the following advantages. Firstly,the binary chirp-like sequence does not generate dangerous delay sincethe binary chirp-like sequence is composed of signals having differentperiods. Secondly, the binary chirp-like sequence provides correctsymbol timing information compared to conventional broadcast systemssince correlation characteristics are similar to those of guard intervalcorrelation and is resistant to noise on a multipath channel compared toa sequence having delta-like correlation such as an m-sequence. Thirdly,when scrambling is performed using the binary chirp-like sequence,bandwidth is less increased compared to the original signal. Fourthly,the binary chirp-like sequence is a binary sequence and thus can be usedto design a device having low complexity.

In the graph showing the waveform of the binary chirp-like sequence, thesolid line represents a waveform corresponding to a real part and adotted line represents an imaginary part. The waveforms of the real partand the Imaginary part of the binary chirp-like sequence correspond tosquare waves.

FIG. 35 illustrates examples of scrambling sequences modified from thebinary chirp-like sequence according to an embodiment of the presentinvention.

The upper right corner of FIG. 35 shows a reversed binary chirp-likesequence obtained by reversely arranging the binary chirp-like sequencein the time domain.

The upper left of FIG. 35 shows a conjugated binary chirp-like sequenceobtained by complex conjugating the binary chirp-like sequence. That is,the real part of the conjugated binary chirp-like sequence equals thereal part of the binary chirp-like sequence and the imaginary part ofthe conjugated binary chirp-like sequence equals the imaginary part ofthe binary chirp-like sequence in terms of absolute value and isopposite to the imaginary part of the binary chirp-like sequence interms of sign.

At the bottom right of FIG. 35 shows a cyclically-shifted binarychirp-like sequence obtained by cyclically shifting the binarychirp-like sequence by a half period, that is, 512.

At the bottom left of FIG. 35 shows a half-negated sequence. A fronthalf period, that is, 0 to 512 of the half-negated chirp-like sequenceequals that of the binary chirp-like sequence and the real part andimaginary part of a rear half period, that is, 513 to 1024 of thehalf-negated chirp-like sequence equals that of the binary chirp-likesequence in terms of absolute value and is opposite to the binarychirp-like sequence in terms of sign.

The average of the above-described scrambling sequence is 0. Even when acontinuous wave interference is generated in a signal and thus a complexDC is present in an output of a differential decoder of the broadcastsignal reception apparatus, the scrambling sequence having an average of0 can be multiplied by the complex DC of the output of the differentialdecoder to prevent the complex DC from affecting signal detectionperformance.

The broadcast signal transmission apparatus according to an embodimentof the present invention can use the scrambling sequences shown in FIGS.34 and 35 differently according to whether the EAS message is includedin the preamble. For example, when the broadcast signal transmissionapparatus does not include the EAS message in the preamble, the guardinterval of the preamble can be scrambled using the scrambling sequenceof FIG. 34. When the broadcast signal transmission apparatus includesthe EAS message in the preamble, the guard interval of the preamble canbe scrambled using one of the scrambling sequences of FIG. 35.

The scrambling sequences shown in the figures are exemplary and may bemodified according to designer.

FIG. 37 illustrates a signaling information structure in the preambleaccording to an embodiment of the present invention.

Specifically, FIG. 37 shows the structure of signaling informationtransmitted through the preamble in the frequency domain according to anembodiment of the present invention.

FIG. 37 illustrates repetition or arrangement of data by the dataformatter 17010 according to the length of a code block of Reed Mullerencoding performed by the Reed Muller encoder 17000. The code block ofReed Muller encoding may be referred to as a Reed Muller FEC block.

The data formatter 17010 may repeat or arrange the signaling informationoutput from the Reed Muller encoder 17000 according to the length of thecode block such that the signaling information corresponds to the numberof active carriers, FIG. 37 shows an embodiment in which the number ofactive carriers is 384.

Accordingly, when the Reed Muller encoder 17000 performs Reed Mullerencoding on a 64-bit block, as shown in the upper side of FIG. 37, thedata formatter 17010 can repeat the same data six times. In this case,the Reed Muller encoder 17000 can use a 1st order Reed Muller code andsignaling information of each Reed Muller code may be 7 bits.

When the Reed Muller encoder 17000 performs Reed Muller encoding on a256-bit block, as shown in the middle of FIG. 37, the data formatter17010 can repeat front 128 bits or rear 128 bits of the 256-bit codeblock or repeat even-numbered 128 bits or odd-numbered 128 bits of the256-bit code block to arrange data as 384 bits. In this case, the ReedMuller encoder 17000 can use a 1st order Reed Muller code and signalinginformation of each Reed Muller code may be 9 bits.

As described above, the signaling information formatted by the dataformatter 17010 may be processed through the cyclic delay block 17020and the interleaver 17030 or not, mapped through the DQPSK/DBPSK mapper17040, scrambled by the scrambler 17050 and then input to the carrierallocation block 17060.

At the bottom of FIG. 37 illustrates a method for allocating thesignaling information to active carriers through the carrier allocationblock 17060 according to an embodiment of the present invention. In thebottom of FIG. 37, b(n) (n being an integer equal to or greater than 0)represents carriers to which data is allocated. In one embodiment, thenumber of carriers is 384. Colored carriers from among the carriersshown in the bottom of FIG. 37 denote active carriers and uncoloredcarriers denote null carriers. Positions of the active carriers shown inthe bottom of FIG. 37 may be changed according to designer.

FIG. 38 illustrates a procedure of processing signaling data transmittedthrough the preamble according to an embodiment of the presentinvention.

The signaling data transmitted through the preamble may include aplurality of signaling sequences. Each signaling sequence may be 7 bits.The number and size of the signaling sequences may be changed accordingto designer.

The upper side of FIG. 38 shows a procedure of processing the signalingdata transmitted through the preamble when the signaling data is 14 bitsaccording to an embodiment of the present invention. In this case, thesignaling data transmitted through the preamble may include twosignaling sequences which may be referred to as signaling 1 andsignaling 2, Signaling 1 and signaling 2 may be the same signalingsequences as the aforementioned signaling sequences S1 and S2.

At the bottom of FIG. 38 shows a procedure of processing the signalingdata transmitted through the preamble when the signaling data is 21 bitsaccording to an embodiment of the present invention. In this case, thesignaling data transmitted through the preamble may include threesignaling sequences which may be referred to as signaling 1, signaling 2and signaling 3. Signaling 1, signaling 2 and signaling 3 may be thesame signaling sequences as the aforementioned signaling sequences S1,S2 and S3.

As shown in FIG. 38, the interleaving block 17030 according to anembodiment of the present invention may sequentially alternately assignS1 and S2 to active carriers.

The number of carriers is 384 and the carriers may be represented bysequential numerals starting from 0 in one embodiment. Accordingly, thefirst carrier according to an embodiment of the present invention can berepresented by b(0), as shown in FIG. 38). Uncolored active carriersshown in FIG. 38 denote null carriers to which S1, S2 or S3 is notarranged (or allocated).

A detailed description will be given of assignment of signalinginformation to signaling fields and active carriers.

Bit sequences of S1 and bit sequences of S2 according to an embodimentof the present invention are signaling sequences which may be allocatedto active carriers in order to transmit independent signalinginformation (or signaling fields) included in the preamble.

Specifically, S1 can carry 3-bit signaling information and can beconfigured in a structure in which a 64-bit sequence is repeated twice.In addition, S1 can be arranged before and after S2. S2 is a 256-bitsequence and can carry 4-bit signaling information. The bit sequences ofS1 and S2 of the present invention may be represented by sequentialnumerals starting from 0 according to one embodiment. Accordingly, thefirst bit sequence of S1 can be represented as S1(0) and the first bitsequence of 52 can be represented as S2(0), Representation of the bitsequences may be changed according to designer.

S1 may carry information for identifying each signal frame included inthe superframe described above with reference to FIG. 10, for example,information indicating an SISO-processed signal frame, MISO-processedsignal frame or FEF, S2 may carry information about an FFT size of thecurrent signal frame or information indicating whether framesmultiplexed in one superframe are of the same type. Information carriedthrough S2 may be changed according to designer.

Signaling 1 and signaling 2 may be respectively encoded into 64-bit ReedMuller codes by the aforementioned Reed Muller encoder. The upper sideof FIG. 38 shows a Reed-Muller-encoded signaling sequence block.

The encoded signaling sequence blocks of signaling 1 and signaling 2 maybe repeated three times by the aforementioned data formatter. The upperside of FIG. 38 shows the repeated signaling sequence block of signaling1 and the repeated signaling sequence block of signaling 2. Since theReed-Muller-encoded signaling sequence block is 64 bits, the signalingsequence block of each of signaling 1 and signaling 2, repeated threetimes, is 192 bits.

Data of signaling 1 and signaling 2, composed of 6 blocks, alternatelyrearranged, sequentially input to the cyclic delay block 17020 and theinterleaver 17030 and processed therein or mapped by the DBPSK/DQPSKmapper 17040 without undergoing processing of the cyclic delay block17020 and the interleaver 17030, and then allocated to 384 carriers bythe aforementioned carrier allocation block, in the upper side of FIG.38, b(0) may denote the first carrier and b(1) and b(2) may denotecarriers. In one embodiment of the present invention, a total of 384carriers b(0) to b(383) may be present. From among carriers shown in thefigure, colored carriers denote active carriers and uncolored carriersdenote null carriers. Active carriers represent carriers to whichsignaling data is allocated and null carriers represent carriers towhich signaling data is not allocated. As described above, the data ofsignaling 1 and signaling 2 may be alternately allocated to carriers.For example, data of signaling 1 can be allocated to b(0), data ofsignaling 2 can be allocated to b(3) and data of signaling 1 can beallocated to b(7). The positions of the active carriers and nullcarriers may-be changed according to designer.

The signaling information transmitted through the preamble according toan embodiment of the present invention may be transmitted through thebit sequences of S1, bit sequences of S2 and bit sequences of S3 asshown in the bottom of the FIG. 38.

S1, S2 and S3 according to an embodiment of the present invention aresignaling sequences which can be allocated to active carriers in orderto transmit independent signaling information (or signaling fields)included in the preamble.

Specifically, S1, S2 and S3 can respectively carry 3-bit signalinginformation and can be configured in a structure in which a 64-bitsequence is repeated twice. Accordingly, S1, S2 and S3 can further carry2-bit signaling information compared to the embodiment of the bottom ofFIG. 38.

In addition, S1 and S2 can carry the signaling information describedwith reference to FIG. 38 and S3 can carry signaling information about aguard interval length (or guard length). Signaling information carriedthrough S1, S2 and S3 may be changed according to designer.

Data of signaling 1, signaling 2 and signaling 3, composed of 6 blocks,is alternately rearranged, sequentially input to the cyclic delay block17020 and the interleaver 17030 and processed thereby or mapped by theDBPSK/DQPSK mapper 17040 without undergoing processing of the cyclicdelay block 17020 and the interleaver 17030, and then allocated to 384carriers by the aforementioned carrier allocation block.

The bit sequences of S1, S2 and S3 may be represented by sequentialnumerals starting from 0, that is, m S1 (0), . . . Referring to thebottom of FIG. 38, the number of carriers is 384 and the carriers may berepresented by sequential numerals starting from 0, that is b(0), . . .according to one embodiment of the present invention. The number andrepresentation method of the carriers may be changed according todesigner.

Referring to FIG. 39, S1, S2 and S3 may be sequentially alternatelyallocated to active carriers in determined positions in the frequencydomain.

Specifically, the bit sequences of S1, S2 and S3 can be sequentiallyallocated to active carriers other than null carriers from among theactive carriers b(0) to b(383).

Each of signaling 1, signaling 2 and signaling 3 may be respectivelyencoded into a 64-bit Reed Muller code by the aforementioned Reed Mullerencoder. FIG. 39 shows a Reed-Muller-encoded signaling sequence block.

The encoded signaling sequence blocks of signaling 1, signaling 2 andsignaling 3 may be repeated twice by the aforementioned data formatter.FIG. 39 shows the repeated signaling sequence block of signaling 1, therepeated signaling sequence block of signaling 2 and the repeatedsignaling sequence block of signaling 3. Since each Reed-Muller-encodedsignaling block is 64 bits, the signaling sequence block of each ofsignaling 1, signaling 2 and signaling 3, repeated twice, is 128 bits.

Signaling 1, signaling 2 and signaling 3, composed of six blocks, may beallocated to 384 carriers by the aforementioned carrier allocationblock. In FIG. 39, b(0) may be the first carrier and b(1) and b(2) maybe other carriers. In one embodiment, 384 carriers b(0) to b(383) may bepresent. Colored carriers from among the carriers shown in the figuredenote active carriers and uncolored carriers denote null carriers.Active carriers may be carriers to which signaling data is allocated andnull carriers may be carriers to which signaling data is not allocated.Data of signaling 1, signaling 2 and signaling 3 may be alternatelyallocated to carriers. For example, data of signaling 1 can be allocatedto b(0), data of signaling 2 can be allocated to b(1), data of signaling3 can be allocated to b(3) and data of signaling 1 can be allocated tob(7). The positions of the active carriers and null carriers shown inthe figure may be changed according to designer.

FIG. 39 illustrates a procedure of processing signaling data transmittedthrough the preamble according to an embodiment of the presentinvention.

In FIG. 39 shows a procedure of processing signaling data transmittedthrough the preamble when the signaling data is 24 bits. In this case,the signaling data transmitted through the preamble may include threesignaling sequences which may be referred to as signaling 1, signaling 2and signaling 3. Signaling 1, signaling 2 and signaling 3 may be thesame signaling sequences as the aforementioned signaling Information S1,S2 and S3. The procedure of processing the signaling data is the same asthe procedure described with reference to the bottom of FIG. 38.

As described above with reference to FIGS. 25 and 26, a signaling datacapacity and a signaling data protection level can be traded off bycontrolling the length of an FEC-encoded signaling data block. That is,while the signaling data capacity increases as the length of thesignaling data block increases, the number of repetitions of the dataformatter decreases and the signaling data protection level is lowered.Accordingly, it is possible to select various signaling capacities.

Furthermore, the interleaver 17030 according to an embodiment of thepresent invention can uniformly interleave data of each signaling fieldin the frequency domain. Accordingly, frequency diversitycharacteristics of the preamble can be maximized and robustness againstfrequency selective fading can be improved.

FIG. 40 shows mathematical expressions representing relationshipsbetween input information and output information or mapping rules of theDQPSK/DBPSK mapper 17040 according to an embodiment of the presentinvention.

The upper side of FIG. 40 shows mathematical expressions representing arelationship between input information and output information or amapping rule when the DQPSK/DBPSK mapper 17040 according to anembodiment of the present invention maps the input signaling informationaccording to DBPSK.

The bottom of FIG. 40 shows mathematical expressions representing arelationship between input information and output information or amapping rule when the DQPSK/DBPSK mapper 17040 according to anembodiment of the present invention maps the input signaling informationaccording to DQPSK.

As shown in FIG. 40, the input information of the DQPSK/DBPSK mapper17040 may be represented as si[n] and sq[n] and the output informationof the DQPSK/DBPSK mapper 17040 may be represented as mi[n] and mq[n]for convenience of description.

FIG. 4l illustrates a differential encoding operation that can beperformed by a preamble insertion module according to an embodiment ofthe present invention.

The preamble insertion module according to an embodiment of the presentinvention may repeat signaling information (S1, S2 and S3 represented assignaling 1, signaling 2 and signaling 3 in FIG. 41) twice. Then, thepreamble insertion module may sequentially alternately arrange repeatedbits of S1, S2 and S3. Alternatively, the data formatter according to anembodiment of the present invention may repeat and arrange the signalinginformation, as described above. Subsequently, the preamble insertionmodule may differential-encode consecutive bits (indicated by curvedarrows in the FIG.). Alternatively, the data formatter or DQPSK/DBPSKmapper according to an embodiment of the present invention maydifferential-encode the consecutive bits, as described above. Thepreamble insertion module may scramble the differentially encodedsignaling bits and sequentially alternately allocate the bits of S1, S2and S3 to corresponding carriers. Alternatively, the carrier allocationmodule according to an embodiment of the present invention may scramblethe differential encoded signaling bits and sequentially alternatelyallocate the bits of S1, S2 and S3 to the corresponding carriers.

FIG. 42 illustrates a differential encoding operation that can beperformed by a preamble insertion module according to another embodimentof the present invention.

Operations of the preamble insertion module according to the presentembodiment shown in FIG. 42 may correspond to the operations of thepreamble insertion modules shown in FIG. 41. In addition, operations ofthe data formatter, DQPSK/DBPSK mapper and carrier allocation modulewhich may be included in the preamble insertion module according to thepresent embodiment, shown in FIG. 42, may correspond to operations ofmodules which may-be included in the preamble insertion module shown inFIG. 41.

However, order of the operations may be changed. Specifically, thepreamble insertion module according to the present embodiment may repeatsignaling information after differential encoding, distinguished fromthe operation of the preamble insertion module shown in FIG. 41. Thatis, the preamble insertion module can sequentially alternately arrangethe unrepeated bits of S1, S2 and S3. Then, the preamble insertionmodule can perform differential encoding of the arranged consecutivebits (indicated by curved arrows in the figure). Then, the preambleinsertion module may repeat the differentially encoded signaling bitsand sequentially alternately allocate the repeated bits to correspondingcarriers.

Operations of a signaling decoder of a preamble detector, which will bedescribed later, may depend on the order of differential encoding anddata repetition of the preamble insertion modules described withreference to FIGS. 41 and 42. Detailed operations of the signalingdecoder will be described later.

FIG. 43 is a block diagram of a correlation detector included in apreamble detector according to an embodiment of the present invention.

Specifically, FIG. 43 shows a configuration of the aforementionedpreamble detector 9300 according to one embodiment, that is, aconfiguration of a preamble correlation detector for detecting theaforementioned robust preamble.

The preamble correlation detector according to an embodiment of thepresent invention may include a normal preamble correlation detector(represented as a normal preamble detector in FIG. 43) and a robustpreamble correlation detector (represented as a robust preamble detectorin FIG. 43).

The robust preamble according to an embodiment of the present inventionmay have a structure in which the scrambled guard interval and dataregion are alternately arranged. The normal preamble correlationdetector may obtain correlation of the first half of the robustpreamble. The robust preamble correlation detector may obtaincorrelation of the second half of the robust preamble.

A description will be given of operation of the normal preamblecorrelation detector when the preamble received by the normal preamblecorrelation detector includes information related to the EAS message andthe broadcast signal transmission apparatus uses the binary chirp-likesequence of FIG. 34 and the half-negated sequence of FIG. 35(d) tosignal the information related to the EAS message through the preamble.

The normal preamble correlation detector may multiply signals (i) and(ii), obtained by delaying received signals (i) r(t) and (ii) r(t) by anFFT size, N, and conjugating the delayed signals, by each other.

The normal preamble correlation detector may generate the signal (ii) byconjugating r(t) and then delaying the conjugated r(t) by the FFT size,N. In FIG. 43, a block conj and a block ND (N Delay) can generate thesignal (ii).

A complex N/2 correlator may output correlation between the signalobtained by multiplying (i) by (ii) and a scrambling sequence. Asdescribed above, the first half period N/2 of the half-negated sequenceequals the first half period N/2 of the binary chirp-like sequence andthe sign of the second half period of the half-negated sequence isopposite to the sign of the second half period N/2 of the binarychirp-like sequence. Accordingly, the sum of outputs of two complex N/2correlators may be correlation with respect to the binary chirp-likesequence and a difference between the outputs of the two complex N/2correlators may be correlation with respect to the half-negatedsequence.

The robust preamble correlation detector may detect correlation on thebasis of the two sequence correlations detected by the normal preambledetector. The robust preamble correlation detector may detectcorrelation of the binary chirp-like sequence by summing (i) correlationdetected by the normal preamble detector and (ii) correlation obtainedby delaying a sequence detected by the normal preamble detector by 2N.

The robust preamble correlation detector can detect correlation bydelaying a sequence detected by the normal preamble detector by 2Ncorresponding to the length of OFDM data and scrambled GI since therobust preamble has a structure in which the OFDM data and scrambled GIare repeated twice.

Complex magnitude blocks of the normal preamble correlation detector andthe robust preamble correlation detector may output complex magnitudevalues of correlations detected through correlators. A peak detectorblock may detect a peak of complex magnitude values of inputcorrelations. The peak detector block may detect a preamble positionfrom the detected peak and perform OFDM symbol timing synchronizationand fractional frequency offset synchronization to output frame startinformation. In addition peak detector block may output informationabout preamble type, that is, the normal preamble or the robust preambleand information (EAS flag) about whether the preamble includes the EASmessage.

FIG. 44 illustrates a signaling decoder of a preamble detector accordingto an embodiment of the present invention.

Specifically, FIG. 44 shows an embodiment of the preamble detector 9300described above, which can perform a re verse of the operation of thepreamble insertion block shown in FIG. 30.

The preamble detector according to an embodiment of the presentinvention may include a correlation detector, an FFT block, an ICFOestimator, a carrier allocation table block, a data extractor and asignaling decoder. Each block may be modified according to designer ormay not be included in the preamble detector.

A description will be given of modules constituting the signalingdecoder and operations thereof.

The signaling decoder may include a descrambler 30000, an average block30010, a differential decoder 30020, a deinterleaver 30030, a cyclicdelay block 30040, an I/Q combiner 30050, a data deformatter 30060 and aReed Muller decoder 30070.

The descrambler 30010 may descramble received signaling data.

When the broadcast signal transmission apparatus repeats signalinginformation and then differential-encodes the repeated signalinginformation, as described with reference to FIG. 41, the average block30010 can be omitted. The differential decoder 30020 may receive thedescrambled signal and perform DBPSK or DQPSK demapping on thedescrambled signal.

Alternatively, when the broadcast signal transmission apparatusdifferential-encodes signaling information and then repeats thedifferential encoded signaling information, as described with referenceto FIG. 42, the average block 30010 may average corresponding symbols ofthe descrambled signaling data and then the differential decoder 30020may perform DBPSK or DQPSK demapping on the averaged signal. The averageblock may calculate a data average on the basis of the number ofrepetitions of the signaling information.

A description will be given of detailed operation of the differentialdecoder 30020.

When a transmitter receives a DQPSK-mapped signal, the differentialdecoder 30020 may perform phase rotation .by π/4 on the differentialdecoded signal. Accordingly, the differential decoded signal can besegmented into in-phase and quadrature components.

When the transmitter has performed interleaving, the deinterleaver 30030may deinterleave the signal output from the differential decoder 30020.

When the transmitter has performed cyclic delay, the cyclic delay block30040 may perform a reverse of the cyclic delay operation performed inthe transmitter.

The I/Q combiner 30050 may combine I and Q components of thedeinterleaver signal or delayed signal.

When the signal received from the transmitter has been DBPSK mapped, theI/Q combiner 30050 can output only the I component of the deinterleaversignal.

Then, the data deformatter 30060 may combine bits of signals output fromthe I/Q combiner 30050 per signaling field to output the signalinginformation. When the broadcast signal transmission apparatus repeatsthe signaling information and then differential encode the repeatedsignaling information, the data deformatter 30060 can average the bitsof the signaling information.

Subsequently, the Reed Muller decoder 30070 may decode the signalinginformation output from the data deformatter 30060.

Accordingly, the broadcast signal reception apparatus according to anembodiment of the present invention can obtain the signaling informationtransmitted using the preamble through the aforementioned procedure.

FIG. 45 illustrates a signaling decoder of a preamble detector accordingto an embodiment of the present invention.

Specifically, FIG. 45 shows an embodiment of the preamble detector 9300described above, which can perform a reverse of the operation of thepreamble insertion block shown in FIG. 32, that is, detect the robustpreamble.

The preamble detector according to an embodiment of the presentinvention may include a correlation detector, an FFT block, an ICFOestimator, a carrier allocation table block, a data extractor and asignaling decoder, as described above. Each block may be modifiedaccording to designer or may not be included in the preamble detector.

Modules constituting the signaling decoder and operations thereof willnow be described.

The signaling decoder may include a descrambler A, a descrambler B, anaverage block, a differential decoder, a deinterleaver, a cyclic delayblock, an I/Q combiner, a data deformatter and a Reed Muller decoder.

Operations of the descrambler A and descrambler B may correspond to theoperation of the aforementioned descrambler 30000.

Operations of other modules may correspond to operations of the modulesshown in FIG. 44.

The descrambler A and descrambler B according to an embodiment of thepresent invention may descramble OFDM data A and OFDM data B bymultiplying the OFDM data A and OFDM data B by a scrambling sequence.Then, the signaling decoder may sum descrambled data output from thedescrambler A and descrambler B. Subsequent operations of the signalingdecoder may be identical to corresponding operations of the signalingdecoder shown In FIG. 44.

FIG. 46 illustrates a signaling decoder of a preamble detector accordingto an embodiment of the present invention.

Specifically, FIG. 46 shows an embodiment of the preamble detector 9300described above, which can perform a reverse of the operation of thepreamble insertion block shown in FIG. 33, that is, detect the robustpreamble. The preamble detector according to an embodiment of thepresent invention may include a correlation detector, an FFT block, anICFO estimator, a carrier allocation table block, a data extractor and asignaling decoder. Each block may be modified according to designer ormay not be included in the preamble detector.

Modules constituting the signaling decoder and operations thereof willnow be described.

The signaling decoder may include a descrambler, an average block, adifferential decoder, a deinterleaver, a cyclic delay block, an I/Qcombiner, a data deformatter A, a data deformatter B and a Reed Mullerdecoder.

Operations of the data deformatter A and data deformatter B maycorrespond to the operation of the aforementioned data deformatter30060. Operations of the descrambler, average block, differentialdecoder, deinterleaver, cyclic delay block and I/Q combiner maycorrespond to the operations of the modules shown in FIG. 44.

Specifically, the data deformatter A and data deformatter B may combinesignaling information corresponding to OFDM data A or OFDM data B fromamong bits of signals output from the I/Q combiner per signaling fieldto output signaling information. Then, the signaling informationcombined per OFDM data output from the data deformatter A and datadeformatter B and per signaling field are combined and input to the ReedMuller decoder module. The Reed Muller decoder module may decode theinput signaling information.

FIG. 47 is a diagram showing a preamble structure according to anembodiment of the present invention.

An upper dashed box of FIG. 47 shows the structure of a normal preamble,and a lower dashed box of FIG. 47 shows the structure of an extendedpreamble according to an embodiment of the present invention.

A description of the normal preamble of the upper dashed box of FIG. 47may be the same as that given above in relation to FIGS. 30 and 31.Guard interval Scrambler Sequence indicated in the figure may refer to ascrambling sequence to be multiplied by a guard interval in the form ofa cyclic prefix.

As described above, a preamble of a future broadcasting system cantransmit basic transmission parameters necessary for the broadcastsignal receiver. That is, the preamble is a special symbol that enablesfast Futurecast UTB system signal detection and provides a set of basictransmission parameters for efficient transmission and reception of thesignal. The basic transmission parameters necessary for the broadcastsignal receiver may include FFT_SIZE, PILOT_MODE, etc. described abovein relation to FIG. 12.

In the future broadcasting system, the throughput of the basictransmission parameters necessary for the broadcast signal receiver maybe increased. In this case, the extended preamble structure representedby the Sower dashed box of FIG. 47 according to an embodiment of thepresent invention may be used to extend data transmission capacity. Theextended preamble may have a form in which a plurality of normalpreambles are repeated. An extended preamble having a form in which twonormal preambles are repeated is now described as an embodiment.

The extended preamble of the lower dashed box of FIG. 47 may include twoOFDM data regions and two scrambled guard interval (GI) regions eachhaving a length of N. That is, the length of the extended preambleaccording to an embodiment of the present invention may be 4N. Thisstructure may be the same as that of the robust preamble described abovein relation to FIG. 31. Accordingly, a description is now given mainlyof the differences from the above-described robust preamble.

The two OFDM data regions included in the extended preamble according toan embodiment of the present invention, i.e., OFDM data A and OFDM dataB, may transmit different signaling data. Accordingly, the extendedpreamble according to an embodiment of the present invention maytransmit signaling data corresponding to an integer multiple of thecapacity of signaling data transmittable by the normal preamble and therobust preamble described above in relation to FIG. 31. For example, ifthe signaling data of the normal preamble is 21 bits, the extendedpreamble according to an embodiment of the present invention maytransmit signaling data of 42 bits.

The different signaling data transmitted by one of OFDM data A or OFDMdata B may include version information of the future broadcastingsystem, category information of emergency event in the Emergency alertsystem. That is, the different signaling data according to an embodimentof the present invention is variable according to the intention of adesigner.

Scrambler sequences (Guard interval Scrambler Sequence 1 and Guardinterval Scrambler Sequence 2 in the FIG.) used to generate scrambledGIs (Scrambled GI A and Scrambled GI B in the FIG.) included in theextended preamble according to an embodiment of the present inventionmay be the same as or different from each other. The scrambler sequencemay be the same as the scrambling sequence described above in relationto FIGS. 31 to 33.

FIG. 48 is a block diagram of a preamble Insertion block according to anembodiment of the present invention.

Specifically, FIG. 48 is a block diagram of an extended preambleinsertion block according to an embodiment of the present invention.Operations of sub-blocks thereof may be the same as those of thesub-blocks of the preamble insertion block described above in relationto FIGS. 30, 32 and 33. Accordingly, a description is now given mainlyof the differences from operation of the above-described normal orrobust preamble insertion block.

As illustrated in FIG. 48, the extended preamble insertion block mayinclude Reed Muller encoders 17000, data formatters 17010, cyclic delayblocks 17020, interleavers 17030, differential quadrature phase shiftkeying (DQPSK)/differential binary phase shift keying (DBPSK) mappers17040, scramblers 17050, carrier allocation blocks 17060, a carrierallocation table block 17070, IFFT blocks 17080, scrambled guardinsertion blocks 17090 and a multiplexing block 17100.

The extended preamble insertion block according to an embodiment of thepresent invention insertion may separately process signaling data 1 andsignaling data 2 along independent paths. Accordingly, the extendedpreamble insertion block according to an embodiment of the presentinvention may include each type of module in a plural number (2 in thisembodiment) as illustrated in the figure. Alternatively, the extendedpreamble insertion block according to an embodiment of the presentinvention may include each type of module in a singular number tosequentially process a plurality of different signaling data.

A plurality of different signaling data for an extended preamble may beprocessed by the Reed Muller encoders 17000, the data formatters 17010,the cyclic delay blocks 17020, the interleavers 17030 and theDQPSK/DBPSK mappers 17040 which operate in the same manner.

After that, Scrambler A and Scrambler B of the extended preambleinsertion block according to an embodiment of the present invention mayuse the same scrambler sequence or different scrambler sequences.

After that, the extended preamble insertion block according to anembodiment of the present invention may generate an extended preamble byallocating signaling information of the preamble to OFDM symbol carriersbased on the same carrier allocation table using the signaling datamultiplexed by the scrambling sequence. Alternatively, although notshown in the figure, the extended preamble insertion block according toan embodiment of the present invention may generate an extended preambleby allocating signaling information of the preamble to OFDM symbolcarriers based on different carrier allocation tables.

The scrambler sequence used to generate the extended preamble accordingto an embodiment of the present invention may be the scrambling sequenceillustrated as graphs in FIGS. 34 and 35.

FIG. 49 is a detailed block diagram of a correlation detector in apreamble detector according to an embodiment of the present invention.

Specifically, this figure corresponds to an embodiment of theabove-described preamble detector 9300, and shows the structure of apreamble correlation detector for detecting the above-described extendedpreamble. Hereinafter, the preamble correlation detector for detectingthe extended preamble is referred to as an extended preamble correlationdetector. This figure shows an example of the extended preamblecorrelation detector in a case when the same scrambler sequence isapplied to two preambles included in the extended preamble according toan embodiment of the present invention.

Operations of sub-blocks of the extended preamble correlation detectoraccording to an embodiment of the present invention may be the same asthose of the sub-blocks of the preamble correlation detector fordetecting the robust preamble which are described above in relation toFIG. 43.

A detailed description is now given of operation of the extendedpreamble correlation detector in an exemplary case when a preamblereceived by the extended preamble correlation detector includesinformation about an EAS message, and the broadcast signal transmitteruses the above-described binary chirp-like sequence of FIG. 34 and thehalf-negated sequence of FIG. 35(d) to signal the information about theEAS message in the preamble.

The extended preamble correlation detector may multiply signals (i) and(ii) obtained by conjugating signals delayed from received signals (i)r(t) and (ii) r(t) by the size of FFT, N.

The extended preamble correlation detector may generate the signal (ii)by conjugating r(t) and then delaying the same by the size of FFT, N. Inthis figure, a conj block and an N delay (ND) block may generate thesignal (ii).

Alter that, a complex N/2 correlator may output correlation between thesignal obtained by multiplying (i) and (ii) and a scrambling sequence.As described above, a first half (N/2) of the half-negated sequence isthe same as a first half (N/2) of the binary chirp-like sequence, and asecond half (N/2) of the half-negated sequence is opposite-signed to asecond half (N/2) of the binary chirp-like sequence. Accordingly, inthis figure, a sum of outputs of two complex N/2 correlators may becorrelation for the binary chirp-like sequence, and the differencebetween the outputs of the two complex N/2 correlators may becorrelation for the half-negated sequence. Operation till now is thesame as that of the above-described robust preamble correlationdetector.

The extended preamble correlation detector may detect correlation basedon the detected sequence correlations. The extended preamble correlationdetector may detect correlation of the binary chirp-like sequence bysumming (i) the sequence correlation corresponding to the sum of theoutputs of the two complex N/2 correlators and (ii) sequence correlationdelayed from the sequence correlation corresponding to the sum of theoutputs of the two complex N/2 correlators, by 2N.

Likewise, the extended preamble correlation detector may detectcorrelation of the half-negated sequence by summing (i) the sequencecorrelation corresponding to the difference between the outputs of thetwo complex N/2 correlators and (ii) sequence correlation delayed fromthe sequence correlation corresponding to the difference between theoutputs of the two complex N/2 correlators, by 2N.

After that, each complex magnitude block of the extended preamblecorrelation detector may output a complex magnitude value of thecorrelation detected by each correlator. A peak detector block maydetect a peak from the input complex magnitude values of thecorrelations. The peak detector may output frame start information bydetecting the location of a preamble from the detected peak andperforming OFDM symbol timing sync and fractional frequency offset sync.In addition, the peak detector may output information about thestructure of the preamble, i.e., whether the preamble is a normalpreamble or a robust preamble, and includes an EAS message (EAS flag),based on the detected peak.

FIG. 50 is a detailed block diagram of a correlation detector in apreamble detector according to another embodiment of the presentinvention.

Specifically, this figure corresponds to another embodiment of theextended preamble correlation detector described above in relation toFIG. 49. This figure shows an example of the extended preamblecorrelation detector in a case when different scrambler sequences areapplied to two preambles included in the extended preamble according toan embodiment of the present invention.

Operations of sub-blocks of the extended preamble correlation detectoraccording to an embodiment of the present invention may be the same asthose of the sub-blocks of the preamble correlation detector fordetecting the robust preamble which are described above in relation toFIG. 43.

The extended preamble correlation detector may multiply signals (i) and(ii) obtained by conjugating signals delayed from received signals (i)r(t) and (ii) r(t) by the size of FFT, N.

The extended preamble correlation defector may generate the signal (ii)by conjugating r(t) and then delaying the same by the size of FFT, N. Inthis figure, a conj block and an N delay (ND) block may generate thesignal (ii). This operation is the same as that of the extended preamblecorrelation detector described above in relation to FIG. 49. Operationtill now is the same as that of the above-described robust preamblecorrelation detector.

After that, each complex correlator may output correlation between thesignal obtained by multiplying (i) and (ii) and a scrambling sequence.The complex correlators of this figure may output sequence correlationsof a plurality of preambles to which different scrambler sequences(scrambler sequence A and scrambler sequence B) are applied. Inaddition, the complex correlators (Complex correlator EAS off A orComplex correlator EAS on A of this FIG.) may selectively operatedepending on whether a plurality of preambles include EAS.

A description is now given of operation of the extended preamblecorrelation detector in a case when a plurality of preambles include EAS(EAS on). The extended preamble correlation detector may defect sequencecorrelation based on two sequence correlations detected from Complexcorrelator EAS on A and Complex correlator EAS on B. The extendedpreamble correlation detector may detect sequence correlation by summing(i) the correlation detected by Complex correlator EAS on B and (ii)correlation delayed from the correlation detected by Complex correlatorEAS on A, by 2N.

After that, each complex magnitude block of the extended preamblecorrelation detector may output a complex magnitude value of thecorrelation detected by each correlator. A peak detector block maydetect a peak from the input complex magnitude values of thecorrelations. The peak detector may output frame start information bydetecting the location of a preamble from the detected peak andperforming OFDM symbol timing sync and fractional frequency offset sync,in addition, the peak detector may output information about thestructure of the preamble, i.e., whether the preamble is a normalpreamble or a robust preamble, and includes an EAS message (EAS flag),based on the detected peak.

The above-described sequence correlation acquisition operation of theextended preamble correlation detector may be the same as that in a casewhen a plurality of preambles do not include EAS (EAS off).

FIG. 51 is a view illustrating a frame structure of a broadcast systemaccording to an embodiment of the present invention.

The above-described cell mapper included in the frame structure modulemay locate cells for transmitting input SISO, MISO or MIMO processed DPdata, cells for transmitting common DP data, and cells for transmittingPLS data in a signal frame according to scheduling information. Then,the generated signal frames may be sequentially transmitted.

A broadcast signal transmission apparatus and transmission methodaccording to an embodiment of the present invention may multiplex andtransmit signals of different broadcast transception systems within thesame RF channel, and a broadcast signal reception apparatus andreception method according to an embodiment of the present invention maycorrespondingly process the signals. Thus, a broadcast signaltransception system according to an embodiment of the present inventionmay provide a flexible broadcast transception system.

Therefore, the broadcast signal transmission apparatus according to anembodiment of the present invention may sequentially transmit aplurality of superframes delivering data related to broadcast service.

The upper portion of FIG. 51 illustrates a superframe according to anembodiment of the present invention, and the middle portion of FIG. 51illustrates the configuration of the superframe according to anembodiment of the present invention. As illustrated in the middleportion of FIG. 51, the superframe may include a plurality of signalframes and a non-compatible frame (NCF). According to an embodiment ofthe present invention, the signal frames are time division multiplexing(TDM) signal frames of a physical layer end, which are generated by theabove-described frame structure module, and the NCF is a frame which isusable for a new broadcast service system in the future.

The broadcast signal transmission apparatus according to an embodimentof the present invention may multiplex and transmit various services,e.g., UHD, Mobile and MISO/MIMO, on a frame basis to simultaneouslyprovide the services in an RF. Different broadcast services may requiredifferent reception environments, transmission processes, etc, accordingto characteristics and purposes of the broadcast services.

Accordingly, different services may be transmitted on a signal framebasis, and the signal frames can be defined as different frame typesaccording to services transmitted therein. Further, data included in thesignal frames can be processed using different transmission parameters,and the signal frames can have different FFT sizes and guard intervalsaccording to broadcast services transmitted therein.

Accordingly, as illustrated in the middle of FIG. 51, the different-typesignal frames for transmitting different services may be multiplexedusing TDM and transmitted within a superframe.

According to an embodiment of the present invention, a frame type may bedefined as a combination of an FFT mode, a guard interval mode and apilot pattern, and information about the frame type may be transmittedusing a preamble portion within a signal frame. A detailed descriptionthereof will be given below.

Further, configuration information of the signal frames included in thesuperframe may be signaled through the above-described PLS, and may varyon a superframe basis.

At the bottom of FIG. 51 is a view illustrating the configuration ofeach signal frame. The signal frame may include a preamble, head/tailedge symbols EH/ET, one or more PLS symbols and a plurality of datasymbols. This configuration is variable according to the intention of adesigner.

The preamble is located at the very front of the signal frame and maytransmit a basic transmission parameter for identifying a broadcastsystem and the type of signal frame, information for synchronization,etc. Thus, the broadcast signal reception apparatus according to anembodiment of the present invention may initially detect the preamble ofthe signal frame, identify the broadcast system and the frame type, andselectively receive and decode a broadcast signal corresponding to areceiver type.

The head/tail edge symbols may be located after the preamble of thesignal frame or at the end of the signal frame. In the presentinvention, an edge symbol located after the preamble may be called ahead edge symbol and an edge symbol located at the end of the signalframe may be called a tail edge symbol. The names, locations or numbersof the edge symbols are variable according to the intention of adesigner. The head/tail edge symbols may be inserted into the signalframe to support the degree of freedom in design of the preamble andmultiplexing of signal frames having different frame types. The edgesymbols may include a larger number of pilots compared to the datasymbols to enable frequency-only interpolation and time interpolationbetween the data symbols. Accordingly, a pilot pattern of the edgesymbols has a higher density than that of the pilot pattern of the datasymbols.

The PLS symbols are used to transmit the above-described PLS data andmay include additional system information (e.g., networktopology/configuration, PAPR use, etc.), frame type ID/configurationinformation, and information necessary to extract and decode DPs.

The data symbols are used to transmit DP data, and the above-describedcell mapper may locate a plurality of DPs in the data symbols.

A description is now given of DPs according to an embodiment of thepresent invention.

FIG. 52 is a view illustrating DPs according to an embodiment of thepresent invention.

As described above, data symbols of a signal frame may include aplurality of DPs. According to an embodiment of the present invention,the DPs may be divided into type 1 to type 3 according to mapping modes(or locating modes) in the signal frame.

The first dashed box, (a) of FIG. 52, illustrates type 1 DPs mapped tothe data symbols of the signal frame. The second dashed box, (b) of FIG.52, illustrates type2 DPs mapped to the data symbols of the signalframe, and the third dashed box, (c) of FIG. 52, illustrates type3 DPsmapped to the data symbols of the signal frame. The three dashed boxes,(a) to (c) of FIG. 52, illustrate only a data symbol portion of thesignal frame, and a horizontal axis refers to a time axis while avertical axis refers to a frequency axis. A description is now given ofthe type1 to type3 DPs.

As illustrated in the first dashed box, (a) of FIG. 52, the type 1 DPsrefer to DPs mapped using TDM in the signal frame.

That is, when the type1 DPs are mapped to the signal frame, a framestructure module (or cell mapper) according to an embodiment of thepresent invention may map corresponding DP cells in a frequency axisdirection. Specifically, the frame structure module (or cell mapper)according to an embodiment of the present invention may map cells of DP0in a frequency axis direction and, if an OFDM symbol is completelyfilled, move to a next OFDM symbol to continuously map the cells of DP0in a frequency axis direction. After the cells of DP0 are completelymapped, cells of DP1 and DP2 may also be mapped to the signal frame inthe same manner. In this case, the frame structure module (or cellmapper) according to an embodiment of the present invention may map thecells with an arbitrary interval between DPs.

Since the cells of the type1 DPs are mapped with the highest density onthe time axis, compared to other-type DPs, the type1 DPs may minimize anoperation time of a receiver. Accordingly, the type1 DPs are appropriateto provide a corresponding service to a broadcast signal receptionapparatus which should preferentially consider power saving, e.g., ahandheld or portable device which operates using a battery.

As illustrated in the second dashed box, (b) of FIG. 52, the type2 DPsrefer to DPs mapped using frequency division multiplexing (FDM) in thesignal frame.

That is, when the type2 DPs are mapped to the signal frame, the framestructure module (or cell mapper) according to an embodiment of thepresent invention, may snap corresponding DP cells in a time axisdirection. Specifically, the frame structure module (or cell mapper)according to an embodiment of the present invention may preferentiallymap cells of DP0 on the time axis at a first frequency of an OFDMsymbol. Then, if the cells of DP0 are mapped to the last OFDM symbol ofthe signal frame on the time axis, the frame structure module (or cellmapper) according to an embodiment of the present invention maycontinuously map the cells of DP0 in the same manner from a secondfrequency of a first OFDM symbol.

Since the cells of the type2 DPs are transmitted with the widestdistribution in time, compared to other-type DPs, the type2 DPs areappropriate to achieve time diversity. However, since an operation timeof a receiver to extract the type2 DPs is longer than that to extractthe type1 DPs, the type2 DPs may not easily achieve power saving.Accordingly, the type2 DPs are appropriate to provide a correspondingservice to a fixed broadcast signal reception apparatus which stablyreceives power supply.

Since cells of each type2 DP are concentrated on a specific frequency, areceiver in a frequency selective channel environment may have problemto receive a specific DP. Accordingly, after cell mapping, if frequencyinterleaving is applied on a symbol basis, frequency diversity may beadditionally achieved and thus the above-described problem may besolved.

As illustrated in the third dashed box, (c) of FIG. 52, the type3 DPscorrespond to an intermediate form between the type1 DPs and the type2DPs and refer to DPs mapped using time & frequency division multiplexing(TFDM) in the signal frame.

When the type3 DPs are mapped to the signal frame, the frame structuremodule (or cell mapper) according to an embodiment of the presentinvention may equally partition the signal frame, define each partitionas a slot, and map cells of corresponding DPs in a time axis directionalong the time axis only within the slot.

Specifically, the frame structure module (or cell mapper) according toan embodiment of the present invention may preferentially map cells ofDP0 on the time axis at a first frequency of a first OFDM symbol. Then,if the cells of DP0 are mapped to the last OFDM symbol of the slot onthe time axis, the frame structure module (or cell mapper) according toan embodiment of the present invention may continuously map the cells ofDP0 in the same manner from a second frequency of the first OFDM symbol.

In this case, a trade-off between time diversity and power saving ispossible according to the number and length of slots partitioned fromthe signal frame. For example, if the signal frame is partitioned into asmall number of slots, the slots have a large length and thus timediversity may be achieved as in the type2 DPs. If the signal frame ispartitioned into a large number of slots, the slots have a small lengthand thus power saving may be achieved as in the type1 DPs.

FIG. 53 is a view illustrating type1 DPs according to an embodiment ofthe present invention.

FIG. 53 illustrates an embodiment in which the type1 DPs are mapped to asignal frame according to the number of slots. Specifically, the firstdashed box, (a) of FIG. 53, shows a result of mapping the type1 DPs whenthe number of slots is 1, and the second dashed box, (b) of FIG. 53,shows a result of mapping the type1 DPs when the number of slots is 4.

To extract cells of each DP mapped in the signal frame, the broadcastsignal reception apparatus according to an embodiment of the presentinvention needs type information of each DP and signaling information,e.g., DP start address information indicating an address to which afirst cell of each DP is mapped, and FEC block number information ofeach DP allocated to a signal frame.

Accordingly, as illustrated in the first dashed box, (a) of FIG. 53, thebroadcast signal transmission apparatus according to an embodiment ofthe present invention may transmit signaling information including DPstart address Information indicating an address to which a first cell ofeach DP is mapped (e.g., DP0_St, DP1_St, DP2_St, DP3_St, DP4_St), etc.

The second dashed box, (b) of FIG. 53, shows a result of mapping thetype1 DPs when the signal frame is partitioned into 4 slots. Cells ofDPs mapped to each slot may be mapped in a frequency direction. Asdescribed above, if the number of slots is large, since cellscorresponding to a DP are mapped and distributed with a certaininterval, time diversity may be achieved. However, since the number ofcells of a DP mapped to a single signal frame is not always divided bythe number of slots, the number of cells of a DP mapped to each slot mayvary. Accordingly, if a mapping rule is established in consideration ofthis, an address to which a first cell of each DP is mapped may be anarbitrary location in the signal frame. A detailed description of themapping method will be given below. Further, when the signal frame ispartitioned into a plurality of slots, the broadcast signal receptionapparatus needs information indicating the number of slots to obtaincells of a corresponding DP. In the present invention, the informationindicating the number of slots may be expressed as N_Slot. Accordingly,the number of slots of the signal frame of the first dashed box, (a) ofFIG. 53, may be expressed as N_Slot=1 and the number of slots of thesignal frame of the second dashed box, (b) of FIG. 53, may be expressedas N_Slot=4.

FIG. 54 is a view illustrating type2 DPs according to an embodiment ofthe present invention.

As described above, cells of a type2 DP are mapped in a time axisdirection and, if the cells of the DP are mapped to the last OFDM symbolof a signal frame on a time axis, the cells of the DP may becontinuously mapped in the same manner from a second frequency of afirst OFDM symbol.

As described above in relation to FIG. 53, even in the case of the type2DPs, to extract cells of each DP mapped in the signal frame, thebroadcast signal reception apparatus according to an embodiment of thepresent invention needs type information of each DP and signalinginformation, e.g., DP start address information indicating an address towhich a first cell of each DP is mapped, and FEC block numberinformation of each DP allocated to a signal frame.

Accordingly, as illustrated in FIG. 54, the broadcast signaltransmission apparatus according to an embodiment of the presentinvention may transmit DP start address information indicating anaddress to which a first cell of each DP is mapped (e.g., DP0_St,DP1_St, DP2_St, DP3_St, DP4_St). Further, FIG. 54 illustrates a ease inwhich the number of slots is 1, and the number of slots of the signalframe of FIG. 54 may be expressed as N_Slot=1.

FIG. 55 is a view illustrating type3 DPs according to an embodiment ofthe present invention.

The type3 DPs refer to DPs mapped using TFDM in a signal frame asdescribed above, and may be used when power saving is required whilerestricting or providing time diversity to a desired level. Like thetype2 DPs, the type3 DPs may achieve frequency diversity by applyingfrequency interleaving on an OFDM symbol basis.

The first dashed box, (a) of FIG. 55 illustrates a signal frame in acase when a DP is mapped to a slot, and the second dashed box, (b) ofFIG. 55 illustrates a signal frame in a case when a DP is mapped to twoor more slots. Both (a) and (b) of FIG. 55 illustrate a case in whichthe number of slots is 4, and the number of slots of the signal framemay be expressed as N_Slot=4.

Further, as illustrated In FIGS. 53 and 54, the broadcast signaltransmission apparatus according to an embodiment of the presentinvention may transmit DP start address information indicating anaddress to which a first cell of each DP is mapped (e.g., DP0_St,DP1_St, DP2_St, DP3_St, DP4_St).

In the second dashed box, (b) of FIG. 55, time diversity different fromthat achieved in the first dashed box, (a) of FIG. 55, may be achieved.In this case, additional signaling information may be needed.

As described above in relation to FIGS. 53 to 55, the broadcast signaltransmission apparatus according to an embodiment of the presentinvention may transmit signaling information including DP start addressinformation indicating an address to which a first cell of each DP ismapped (e.g., DP0_St, DP1_St, DP2_St, DP3_St, DP4_St), etc. In thiscase, the broadcast signal transmission apparatus according to anembodiment of the present invention may transmit only the start addressinformation of DP0 which is initially mapped, and transmit an offsetvalue based on the start address information of DP0 for the other DPs.If the DPs are equally mapped, since mapping intervals of the DPs arethe same, a receiver may achieve start locations of the DPs usinginformation about a start location of an initial DP, and an offsetvalue. Specifically, when the broadcast signal transmission apparatusaccording to an embodiment of the present invention transmits offsetinformation having a certain size based on the start address informationof DP0, the broadcast signal reception apparatus according to anembodiment of the present invention may calculate a start location ofDP1 by adding the above-described offset information to the startaddress information of DP0. In the same manner, the broadcast signalreception apparatus according to an embodiment of the present inventionmay calculate a start location of DP2 by adding the above-describedoffset information twice to the start address information of DP0. If theDPs are not equally mapped, the broadcast signal transmission apparatusaccording to an embodiment of the present invention may transmit thestart address information of DP0 and offset values (OFFSET 1, OFFSET 2,. . . ) indicating intervals of the other DPs based on the startlocation of DP0. In this case, the offset values may be the same ordifferent. Further, the offset value(s) may be included and transmittedin PLS signaling information or in-band signaling information to bedescribed below with reference to FIG. 68. This is variable according tothe intention of a designer.

A description is now given of a method for mapping a DP using resourceblocks (RBs) according to an embodiment of the present invention.

An RB is a certain unit block for mapping a DP and may be called a datamapping unit in the present invention. RB based resource allocation isadvantageous in intuitively and easily processing DP scheduling andpower saving control. According to an embodiment of the presentinvention, the name of the RB is variable according to the intention ofa designer and the size of RB may be freely set within a range whichdoes not cause a problem in bit-rate granularity.

The present invention may exemplarily describe a case in which the sizeof RB is a value obtained by multiplying or dividing the number ofactive carriers (NoA) capable of transmitting actual data in an OFDMsymbol, by an integer. This is variable according to the intention of adesigner. If the RB has a large size, resource allocation may besimplified. However, the size of RB indicates a minimum unit of anactually supportable bit rate and thus should be determined withappropriate consideration.

FIG. 56 is a view illustrating RBs according to an embodiment of thepresent invention.

FIG. 56 illustrates an embodiment in which DP0 is mapped to a signalframe using RBs when the number of FEC blocks of DP0 is 10. A case inwhich the length of LDPC blocks is 64K and a QAM modulation value is 256QAM as transmission parameters of DP0, a FFT mode of the signal frame is32K, and a scattered pilot pattern is PP32-2 (i.e., the interval ofpilots delivering carriers is Dx=32, and the number of symbols includedin a scattered pilot sequence is Dy=2) is described as an example. Inthis case, the size of FEC block corresponds to 8100 cells, and NoA canbe assumed as 27584. Assuming that the size of RB is a value obtained bydividing NoA by 4, the size of RB corresponds to 6896 cells and may beexpressed as L_RB=NoA/4.

In this case, when the size of FEC blocks and the size of RBs arecompared on a cell basis, a relationship of the size of 10×FECblocks=the size of 11×RBs+5144 cells is established. Accordingly, to mapthe 10 FEC blocks to a single signal frame on an RB basis, the framestructure module (or cell mapper) according to an embodiment of thepresent invention may map data of the 10 FEC blocks sequentially to the11 RBs to map the 11 RBs to a current signal frame, and map theremaining data corresponding to the 5144 cells to a next signal frametogether with next FEC blocks.

FIG. 57 is a view illustrating a procedure for mapping RBs to framesaccording to an embodiment of the present invention.

Specifically, FIG. 57 illustrates a case in which contiguous signalframes are transmitted.

When a variable bit rate is supported, each signal frame may have adifferent number of FEC blocks transmittable therein.

The first dashed box, (a) of FIG. 57, illustrates a case in which thenumber of FEC blocks to be transmitted in signal frame N is 10, a casein which the number of FEC blocks to be transmitted in signal frame N+1is 9, and a case in which the number of FEC blocks to be transmitted insignal frame N+2 is 11.

The second dashed box, (b) of FIG. 57, illustrates a ease in which thenumber of RE to be mapped to signal frame N is 11, a case in which thenumber of RB to be mapped to signal frame NT+1 is 11, and a case inwhich the number of RB to be mapped to signal frame N+2 is 13.

The third dashed box, (c) of FIG. 57, shows a result of mapping the RBsto signal frame N, signal frame N+1 and signal frame N+2.

As illustrated in (a) and (b) of FIG. 57, when the number of FEC blocksto be transmitted in signal frame N is 10, since the size of 10 FECblocks equals to a value obtained by adding 5144 cells to the size of 11RBs, the 11 RBs may be mapped to and transmitted in signal frame N asillustrated in the third dashed box, (c) of FIG. 57.

In addition, as illustrated in the center of FIG. 57, i.e. (b), theremaining 5144 cells form an initial part of a first RB among 11 RBs tobe mapped to signal frame N+1. Accordingly, since a relationship of 5144cells+the size of 9 FEC blocks=the size of 11 RBs+2188 cells isestablished, 11 RBs are mapped to and transmitted in signal frame N+1and the remaining 2188 cells form an initial part of a first RB among 13RBs to be mapped to signal frame N+2. In the same manner, since arelationship of 2188 cells+the size of 11 FEC blocks=the size of 13RBs+1640 cells is established, 13 RBs are mapped to and transmitted insignal frame N+2 and the remaining 1640 cells are mapped to andtransmitted in a next signal frame. The size of FEC blocks is not thesame as the size of NoA and thus dummy cells can be inserted. However,according to the method illustrated in FIG. 57, there is no need toinsert dummy cells and thus actual data may be more efficientlytransmitted. Further, time interleaving or processing similar theretomay be performed on RBs to be mapped to a signal frame before the RBsare mapped to the signal frame and This is variable according to theintention of a designer.

A description is now given of a method of mapping DPs to a signal frameon an RB basis according to the above-described types of the DPs.

Specifically, in the present invention, the RB mapping method isdescribed by separating a ease in which a plurality of DPs are allocatedto all available RBs in a signal frame from a case in which the DPs areallocated to only some RBs. The present invention may exemplarilydescribe a case in which the number of DPs is 3, the number of RBs in asignal frame is 80, and the size of RB is a value obtained by dividingNoA by 4. This case may be expressed as follows.

Number of DPs, N_DP=3

Number of RBs in a signal frame, N_RB=80

Size of RB, L_RB=NoA/4

Further, the present invention may exemplarily describe a case in whichDP0 fills 31 RBs, DP1 fills 15 RBs, and DP2 fills 34 RBs, as the case inwhich a plurality of DPs (DP0, DP1, DP2) are allocated to available RBsin a signal frame. This case may be expressed as follows.

{DP0,DP1,DP2}={31,15,34}

In addition, the present invention may exemplarily describe a case inwhich DP0 fills 7 RBs, DP1 fills 5 RBs, and DP2 fills 6 RBs, as the easein which a plurality of DPs (DP0, DP1, DP2) are allocated to only someRBs in a signal frame. This case may be expressed as follows.

{DP0,DP1,DP2}={7,5,6}

FIGS. 59 to 60 illustrate RB mapping according to the types of DPs.

The present invention may exemplarily define the following values todescribe an RB mapping rule according to the type of each DP.

L_Frame: Number of OFDM symbols in a signal frame

N_Slot: Number of slots in a signal frame

L_Slot: Number of OFDM symbols in a slot

N_RB_Sym: Number of RBs in an OFDM symbol

N_RB: Number of RBs in a signal frame

FIG. 58 is a view illustrating RB mapping of type1 DPs according to anembodiment of the present invention.

FIG. 58 illustrates a single signal frame, and a horizontal axis refersto a time axis while a vertical axis refers to a frequency axis. Acolored block located at the very front of the signal frame on the timeaxis corresponds to a preamble and signaling portion. As describedabove, according to an embodiment of the present invention, a pluralityof DPs may be mapped to a data symbol portion of the signal frame on aRB basis.

The signal frame illustrated in FIG. 58 consists of 20 OFMD symbols(L_Frame=20) and includes 4 slots (N_Slot=4). Further, each slotincludes 5 OFDM symbols (L_Slot=5) and each OFDM symbol is equallypartitioned into 4 RBs (N_RB_Sym=4). Accordingly, a total number of RBsin the signal frame is L_Frame*N_RB Sym which corresponds to 80.

Numerals indicated in the signal frame of FIG. 58 refer to the order ofallocating RBs in the signal frame. Since the type1 DPs are sequentiallymapped in a frequency axis direction, it can be noted that the order ofallocating RBs is sequentially increased on the frequency axis. If theorder of allocating RBs is determined, corresponding DPs may be mappedto ultimately allocated RBs in the order of time. Assuming that anaddress to which each RB is actually mapped in the signal frame (i.e.,RB mapping address) is j, j may have a value from 0 to N_RB-1. In thiscase, if an RB input order is defined as i, i may have a value of 0, 1,2, . . . . N_RB-1 as illustrated in FIG. 58. if N_Slot-1, since the RBmapping address and the RB input order are the same (j=i), input RBs maybe sequentially mapped in ascending order of j. If N_Slot >1, RBs to bemapped to the signal frame may be partitioned and mapped according tothe number of slots, N_Slot. In this case, the RBs may be mappedaccording to a mapping rule expressed as an equation illustrated at thebottom of FIG. 58.

FIG. 59 is a view illustrating RB mapping of type2 DPs according to anembodiment of the present invention.

Like the signal frame illustrated in FIG. 58, a signal frame illustratedin FIG. 59 consists of 20 OFMD symbols (L_Frame=20) and includes 4 slots(N_Slot==4). Further, each slot includes 5 OFDM symbols (L_Slot=5) andeach OFDM symbol is equally partitioned into 4 RBs (N_RB_Sym=4).Accordingly, a total number of RBs in the signal frame isL_(d—)Frame*N_RB_Sym which corresponds to 80.

As described above in relation to FIG. 58, assuming thai an address towhich each RB is actually mapped in the signal frame (i.e., RB mappingaddress) is j, j may have a value from 0 to N_RB-1. Since the type2 DPsare sequentially mapped in a time axis direction, it can be noted thatthe order of allocating RBs is sequentially increased in a time axisdirection. If the order of allocating RBs is determined, correspondingDPs may be mapped to ultimately allocated RBs in the order of time.

As described above in relation to FIG. 58, when an RB input order isdefined as i, if N_Slot=1, since j=i, input RBs may be sequentiallymapped in ascending order of j. If N_Slot >1, RBs to be mapped to thesignal frame may be partitioned and mapped according to the number ofslots, N_Slot. In this ease, the RBs may be mapped according to amapping rule expressed as an equation illustrated at the bottom of FIG.59.

The equations illustrated in FIGS. 58 and 59 to express the mappingrules have no difference according to the types of DPs. However, sincethe type1 DPs are mapped in a frequency axis direction while the type2DPs are mapped in a time axis direction, different RB mapping resultsare achieved due to the difference in mapping direction.

FIG. 60 is a view illustrating RB mapping of type3 DPs according to anembodiment of the present invention.

Like the signal frames illustrated in FIGS. 59 and 59, a signal frameillustrated in FIG. 60 consists of 20 OFMD symbols (L_Frame=20) andincludes 4 slots (N_Slot=4). Further, each slot includes 5 OFDM symbols(L_Slot=5) and each OFDM symbol is equally partitioned into 4 RBs(N_RB_Sym=4). Accordingly, a total number of RBs in the signal frame isL_Frame*N_RB_Sym which corresponds to 80.

An RB mapping address of the type3 DPs may be calculated according to anequation illustrated at the bottom of FIG. 60. That is, if N_Slot=1, theRB mapping address of the type3 DPs is the same as the RB mappingaddress of the type2 DPs. The type2 and type3 DPs are the same in thatthey are sequentially mapped in a time axis direction but are differentin that the type2 DPs are mapped to the end of a first frequency of thesignal frame and then continuously mapped from a second frequency of afirst OFDM symbol while the type3 DPs are mapped to the end of a firstfrequency of a slot and then continuously mapped from a second frequencyof a first OFDM symbol of the slot in a time axis direction. Due to thisdifference, when the type3 DPs are used, time diversity may berestricted by L_Slot and power saving may be achieved on L_Slot basis.

FIG. 61 is a view illustrating RB mapping of type 1 DPs according toanother embodiment of the present invention.

The first dashed box, (a) of FIG. 61 illustrates an RB mapping order ina case when type1 DP0, DP1 and DP2 are allocated to available RBs in asignal frame, and the second dashed box, (h) of FIG. 61, illustrates anRB mapping order in a case when each of type1 DP0, DP1 and DP2 ispartitioned and allocated to RBs included In different slots in a signalframe. Numerals indicated in the signal frame refer to the order ofallocating RBs. If the order of allocating RBs is determined,corresponding DPs may be mapped to ultimately allocated RBs in the orderof time.

The first dashed box, (a) of FIG. 61, illustrates an RB mapping order ina case when N_Slot=1 and {DP0, DP1, DP2}={31,15,34}.

Specifically, DP0 may be mapped to RBs in a frequency axis directionaccording to the order of the RBs and, if an OFDM symbol is completelyfilled, move to a next OFDM symbol on the time axis to be continuouslymapped in a frequency axis direction. Accordingly, if DP0 is mapped toRB0 to RB30, DP1 may be continuously mapped to RB31 to RB45 and DP2 maybe mapped to RB46 to RB79.

To extract RBs to which a corresponding DP is mapped, the broadcastsignal reception apparatus according to an embodiment of the presentinvention needs type information of each DP (DP_Type) and the number ofequally partitioned slots (N_Slot), and needs signaling informationincluding DP start address information of each DP (DP_RB_St), FEC blocknumber information of each DP to be snapped to a signal frame(DP_N_Block), start address information of an FEC block mapped in afirst RB (DP_FEC_St), etc.

Accordingly, the broadcast signal transmission apparatus according to anembodiment of the present invention may also transmit theabove-described signaling information.

The second dashed box, (b) of FIG. 61, illustrates an RB mapping orderin a case when N_Slot=4 and {DP0, DP1, DP2}={31,15,34}.

Specifically, the second clashed box, (b) of FIG. 61, shows a result ofpartitioning DP0, DP1 and DP2 and then sequentially mapping thepartitions of each DP to slots on an RB basis in the same manner as thecase in which N_Slot=1. An equation expressing a rule for partitioningRBs of each DP is illustrated at the bottom of FIG. 61. In the equationillustrated in FIG. 61, parameters s, N_RB_DP and N_RB_DP(s) may bedefined as follows.

s: Slot index, s=0,1,2, . . . , N_Slot-1.

N_RB_DP: Number of RBs of a DP to be mapped to a signal frame

N_RB_DP(s): Number of RBs of a DP to be mapped to a slot of slot index s

According to an embodiment of the present invention, since N_RB_DP=31for DP0, according to the equation illustrated in FIG. 61, the number ofRBs ofDP0 to be mapped to a first slot may be N_RB_DP(0)=8, the numberof RBs ofDP0 to be mapped to a second slot may be N_RB_DP(1)=8, thenumber of RBs of DP0 to be mapped to a third slot may be N_RB_DP(2)=8,and the number of RBs ofDP0 to be mapped to a fourth slot may beN_RB_DP(3)=7. In the present invention, the numbers of RBs of DP0partitioned to be mapped to the slots may be expressed as {8,8,8,7}.

In the same manner, DP1 may be partitioned into {4,4,4,3} and DP2 may bepartitioned into {9,9,8,8}.

The RBs of each partition of a DP may be sequentially mapped in eachslot using the method of the above-described case in which N_Slot=l. Inthis case, to equally fill all slots, the partitions of each DP may besequentially mapped from a slot having a smaller slot index s amongslots to which a smaller number of RBs of other DPs are allocated.

In the case of DP1, since RBs of DP0 are partitioned into {8,8,8,7} andmapped to the slots in the order of s=0,1,2,3, it can be noted that thesmallest number of RBs of DP0 are mapped to the slot having a slot indexs=3. Accordingly, RBs of DP1 may be partitioned into {4,4,4,3} andmapped to the slots in the order of s=3,0,1,2. In the same manner, sincethe smallest number of RBs of DP0 and DP1 are allocated to slots havingslot index s=2 and 3 but s=2 is smaller, RBs of DP2 may be partitionedinto {9,9,8,8} and mapped to the slots in the order of s=2,3,0,1.

FIG. 62 is a view illustrating RB mapping of type1 DPs according toanother embodiment of the present invention.

FIG. 62 illustrates an embodiment in which the above-described RBmapping address of the type1 DPs is equally applied. An equationexpressing the above-described RB mapping address is illustrated at thebottom of FIG. 62. Although a mapping method and procedure in FIG. 62are different from those described above in relation to FIG. 61, sincemapping results thereof are the same, the same mapping characteristicsmay be achieved. According to the mapping method of FIG. 62. RB mappingmay be performed using a single equation irrespective of the value ofN_Slot.

FIG. 63 is a view illustrating RB mapping of type1 DPs according toanother embodiment of the present invention.

The first dashed box, (a) of FIG. 63, illustrates an RB mapping order ina case when type1 DP0, DP1 and DP2 are allocated to only some RBs in asignal frame, and the second dashed box, (b) of FIG. 63, illustrates anRB mapping order in a case when each of type1 DP0, DP1 and DP2 ispartitioned and allocated to only some RBs included in different slotsin a signal frame. Numerals indicated in the signal frame refer to theorder of allocating RBs. If the order of allocating RBs is determined,corresponding DPs may be mapped to ultimately allocated RBs in the orderof time.

The first dashed box, (a) of FIG. 63, illustrates an RB mapping order ina case when N_Slot=1 and {DP0, DP1, DP2}={7,5,6}.

Specifically, DP0 may be mapped to RBs in a frequency axis directionaccording to the order of the RBs and, if an OFDM symbol is completelyfilled, move to a next OFDM symbol on the time axis to be continuouslymapped in a frequency axis direction. Accordingly, if DP0 is mapped toRB0 to RB6, DP1 may be continuously mapped to RB7 to RB11 and DP2 may bemapped to RB12 to RB17.

The second dashed box, (b) of FIG. 63, illustrates an RB mapping orderin a case when N_Slot=4 and {DP0, DP1, DP2}={7,5,6}.

The second dashed box, (b) of FIG. 63, illustrates embodiments in whichRBs of each DP are partitioned according to the RB partitioning ruledescribed above in relation to FIG. 61 and are mapped to a signal frame.Detailed procedures thereof have been described above and thus are notdescribed here.

FIG. 64 is a view illustrating RB mapping of type2 DPs according toanother embodiment of the present invention.

The first dashed box, (a) of FIG. 64, illustrates an RB mapping order ina case when type2 DP0, DP1 and DP2 are allocated to available RBs in asignal frame, and the second dashed box, (b) of FIG. 64, illustrates anRB mapping order in a case when each of type2 DP0, DP1 and DP2 ispartitioned and allocated to RBs included in different slots in a signalframe. Numerals indicated in the signal frame refer to the order ofallocating RBs. If the order of allocating RBs is determined,corresponding DPs may be mapped to ultimately allocated RBs in the orderof time.

The first dashed box, (a) of FIG. 64, illustrates an RB mapping order ina case when N_Slot=1 and {DP0, DP1, DP2}={31,15,34}.

Since RBs of type2 DPs are mapped to the end of a first frequency of thesignal frame and then continuously mapped from a second frequency of afirst OFDM symbol, time diversity may be achieved. Accordingly, if DP0is mapped to RB0 to RB19 on a time axis and then continuously mapped toRB20 to RB30 of the second frequency, DP1 may be mapped to RB31 to RB45in the same manner and DP2 may be mapped to RB46 to RB79.

To extract RBs to which a corresponding DP is mapped, the broadcastsignal reception apparatus according to an embodiment of the presentinvention needs type information of each DP (DP_Type) and the number ofequally partitioned slots (N_Slot), and needs signaling informationincluding DP start address Information of each DP (DP_RB_St), FEC blocknumber information of each DP to be mapped to a signal frame(DP_N_Block), start address information of an FEC block mapped in afirst RB (DP_FEC_St), etc.

Accordingly, the broadcast signal transmission apparatus according to anembodiment of the present invention may also transmit theabove-described signaling information.

The second dashed box, (b) of FIG. 64, illustrates an RB mapping orderin a case when N_Slot=4 and {DP0, DP1, DP2}={31,15,34}.

A first signal frame of the second dashed box, (b) of FIG. 64, shows aresult of performing RB mapping according to the RB partitioning ruledescribed above in relation to FIG. 61, and a second signal frame of thesecond dashed box, (b) of FIG. 64, shows a result of performing RBmapping by equally applying the above-described RB mapping address ofthe type2 DPs. Although mapping methods and procedures of the above twoeases are different, since mapping results thereof are the same, thesame mapping characteristics may be achieved. In this case, RB mappingmay be performed using a single equation irrespective of the value ofN_Slot.

FIG. 65 is a view illustrating RB mapping of type2 DPs according toanother embodiment of the present invention.

The first dashed box, (a) of FIG. 65, illustrates an RB mapping order ina case when type2 DP0, DP1 and DP2 are allocated to only some RBs in asignal frame, and the second dashed box, (b) of FIG. 65, illustrates anRB mapping order in a case when each of type2 DP0, DP1 and DP2 ispartitioned and allocated to only some RBs included in different slotsin a signal frame. Numerals indicated in the signal frame refer to theorder of allocating RBs. If the order of allocating RBs is determined,corresponding DPs may be snapped to ultimately allocated RBs in theorder of time.

The first dashed box, (a) of FIG. 65, Illustrates an RB mapping order ina case when N_Slot=1 and {DP0, DP1, DP2}={7,5,6}.

Specifically, DP0 may be mapped to RBs in a time axis directionaccording to the order of the RBs and, if DP0 is mapped to RB0 to RB6,DP1 may be continuously mapped to RB7 to RB11 and DP2 may be mapped toRB12 to RB17.

The second dashed box, (b) of FIG. 65, illustrates an RB mapping orderin a case when N_Slot=4 and {DP0, DPS, DP2}={7,5,6}.

The second dashed box, (b) of FIG. 65, illustrates embodiments in whichRBs of each DP are partitioned according to the RB partitioning ruledescribed above in relation to FIG. 61 and are mapped to a signal frame.Detailed procedures thereof have been described above and thus are notdescribed here.

FIG. 66 is a view illustrating RB mapping of type3 DPs according toanother embodiment of the present invention.

The first dashed box, (a) of FIG. 66, illustrates an RB mapping order ina case when each of type3 DP0, DP1 and DP2 is partitioned and allocatedto RBs included in different slots in a signal frame, and The seconddashed box, (b) of FIG. 66, illustrates an RB mapping order in a casewhen each of type3 DP0, DP1 and DP2 is partitioned and allocated to onlysome RBs included in a slot in a signal frame. Numerals Indicated in thesignal frame refer to the order of allocating RBs. If the order ofallocating RBs is determined, corresponding DPs may be mapped toultimately allocated RBs in the order of time.

The first dashed box, (a) of FIG. 66, illustrates an RB mapping order ina case when N_Slot=4 and {DP0, DP1, DP2}={31,15,34}.

A first signal frame of the first dashed box, (a) of FIG. 66,illustrates an embodiment in which the above-described RB mappingaddress of the type3 DPs is equally applied. A second signal frame ofthe first dashed box, (a) of FIG. 66, illustrates an embodiment inwhich, when the number of RBs of a DP is greater than that of a slot,time diversity is achieved by changing a slot allocation order.Specifically, the second signal frame of the first dashed box, (a) ofFIG. 66, corresponds to an embodiment in which, when the number of RBsofDP0 allocated to a first slot of the first signal frame is greaterthan that of the first slot, the remaining RBs ofDP0 are allocated to athird slot.

The second dashed box, (b) of FIG. 66, illustrates an RB mapping orderin a case when N_Slot=4 and {DP0, DP1, DP2}={7,5,6}.

Further, to extract RBs to which a corresponding DP is mapped, thebroadcast signal reception apparatus according to an embodiment of thepresent: invention needs type information of each DP (DP_Type) and thenumber of equally partitioned slots (N_Slot), and needs signalinginformation including DP start address information of each DP(DP_RB_St), FEC block number information of each DP to be mapped to asignal frame (DP_N_Block), start address information of an FEC blockmapped in a first RB (DP_FEC_St), etc.

Accordingly, the broadcast signal transmission apparatus according to anembodiment of the present invention may also transmit theabove-described signaling information.

FIG. 67 is a view Illustrating RB mapping of type3 DPs according toanother embodiment of the present invention.

FIG. 67 illustrates RB mapping in a case when N_Slot=1 and {DP0, DP1,DP2}={7,5,6}. As illustrated in FIG. 67, RBs of each DP may be mapped onan arbitrary-block basis in a signal frame. In this case, the broadcastsignal reception apparatus according to an embodiment of the presentinvention needs additional signaling information as well as theabove-described signaling information to extract RBs to which acorresponding DP is mapped.

As such, the present invention may exemplarily describe a case in whichDP end address information of each DP (DP_RB_Ed) is additionallytransmitted. Accordingly, the broadcast signal transmission apparatusaccording to an embodiment of the present invention may map RBs of theDP on an arbitrary block basis and transmit the above-describedsignaling information, and the broadcast signal reception apparatusaccording to an embodiment of the present invention may detect anddecode the RBs of the DP mapped on an arbitrary block basis, usingDP_RB_St information and DP RB Ed information included in theabove-described signaling information. When this method is used, free RBmapping is enabled and thus DPs may be mapped with different RB mappingcharacteristics.

Specifically, as illustrated in FIG. 67, RBs of DP0 may be mapped in acorresponding block in a time axis direction to achieve time diversitylike type2 DPs, RBs of DP1 may be mapped in a corresponding block in afrequency axis direction to achieve the power saving effect like type1DPs. Besides, RBs of DP2 may be mapped in a corresponding block inconsideration of time diversity and power saving like type3 DPs.

Further, even in a case when RBs are not mapped in the wholecorresponding block like DP1, the broadcast signal reception apparatusmay accurately detect the locations of RBs to be acquired, using theabove-described signaling information, e.g., DP_FEC_St information,DP_N_Block information, DP RB St Information and DP_RB_Ed information,and thus a broadcast signal may be efficiently transmitted and received.

FIG. 68 is a view illustrating signaling information according to anembodiment of the present invention.

FIG. 68 illustrates the above-described signaling information related toRB mapping according to DP types, and the signaling information may betransmitted using signaling through a PLS (hereinafter referred to asPLS signaling) or in-band signaling.

Specifically, the left side dashed box, (a) of FIG. 68, illustratessignaling information transmitted through a PLS, and the right sidedashed box, (b) of FIG. 68, illustrates signaling informationtransmitted through in-band signaling.

As illustrated in FIG. 68, the signaling information related to RBmapping according to DP types may include N_Slot information, DP_Typeinformation, DP_N_Block information, DP_RB_St information, DP_FEC_Stinformation and DP_N_Block information.

The signaling information transmitted through PLS signaling is the sameas the signaling information transmitted through in-band signaling.However, a PLS includes information about all DPs included in acorresponding signal frame for service acquisition and thus thesignaling information other than N_Slot information and DP_Typeinformation may be defined within a DP loop for defining informationabout every DP. On the other hand, in-band signaling is used to acquirea corresponding DP and thus is transmitted for each DP. As such, in-bandsignaling is different from PLS signaling in that a DP loop for defininginformation about every DP is not necessary. A brief description is nowgiven of the signaling information.

N_Slot information: Information indicating the number of slotspartitioned form a signal frame, which may have the size of 2 bits.According to an embodiment of the present invention, the number of slotsmay be 1,2,4,8.

DP_Type information: Information indicating the type of a DP, which maybe one of type 1, type 2 and type 3 as described above. This informationis extensible according to the intention of a designer and may have thesize of 3 bits.

DP_N_Block_Max information: Information indicating the maximum number ofFEC blocks of a corresponding DP or a value equivalent thereto, whichmay have a size of 10 bits.

DP_RB_St information: Information indicating an address of a first RB ofa corresponding DP, and the address of an RB may be expressed on an RBbasis. This information may have a size of 8 bits.

DP_FEC_St information: Information indicating a first address of an FECblock of a corresponding DP to be mapped to a signal frame, and theaddress of an FEC block may be expressed on a cell basis. Thisinformation may have a size of 13 bits.

DP_N_Block information: Information indicating the number of FEC blocksof a corresponding DP to be mapped to a signal frame or a valueequivalent thereto, which may have a size of 10 bits.

The above-described signaling information may vary name, size, etc,thereof according to the intention of a designer in consideration of thelength of a signal frame, the size of time interleaving, the size of RB,etc.

Since PLS signaling and in-band signaling have a difference according touses thereof as described above, for more efficient transmission,signaling information may be omitted for PLS signaling and in-bandsignaling as described below.

First, a PLS includes information about all DPs included in acorresponding signal frame. Accordingly, DPs are completely andsequentially mapped to the signal frame in the order of DP0, DP1, DP2, .. . , the broadcast signal reception apparatus may perform calculationto achieve DP_RB_St information. In this case, DP_RB_St information maybe omitted.

Second, in the case of in-band signaling, the broadcast signal receptionapparatus may acquire DP_FEC_St information of a next signal frame usingDP_N_Block information of a corresponding DP. Accordingly, DP_FEC_Stinformation may be omitted.

Third, in the case of in-band signaling, when N_Slot information,DP_Type information and DP_N_Block_Max information which influencemapping of a corresponding DP are changed, a 1-bit signal indicatingwhether the corresponding information is changed may be used, or thechange may be signaled. In this case, additional N_Slot information,DP_Type information and DP_N_Block_Max information may be omitted.

That is, DP_RB_St information may be omitted in the PLS, and signalinginformation other than DP_RB_St information and DP_N_Block informationmay be omitted in in-band signaling. This is variable according to theintention of a designer.

FIG. 69 is a graph showing the number of bits of a PLS according to thenumber of DPs according to an embodiment of the present invention.

Specifically, FIG. 69 shows an increase in number of bits for PLSsignaling in a case when signaling information related to RB mappingaccording to DP types is transmitted through a PLS, as the number of DPsis increased.

A dashed line refers to a case in which every related signalinginformation is transmitted (Default signaling), and a solid line refersto a case in which the above-described types of signaling informationare omitted (Efficient signaling). As the number of DPs is increased, ifcertain types of signaling information are omitted, it is noted that thenumber of saved bits is linearly increased.

FIG. 70 is a view illustrating a procedure for demapping DPs accordingto an embodiment of the present invention.

As illustrated in the top of FIG. 70, the broadcast signal transmissionapparatus according to an embodiment of the present invention maytransmit contiguous signal frames 35000 and 35100. The configuration ofeach signal frame is as described above.

As described above, when the broadcast signal transmission apparatusmaps DPs of different types to a corresponding signal frame on an RBbasis and transmits the signal frame, the broadcast signal receptionapparatus may acquire a corresponding DP using the above-describedsignaling information related to RB mapping according to DP types.

As described above, the signaling information related to RB mappingaccording to DP types may be transmitted through a PLS 35010 of thesignal frame or through in-band signal 35020. The left bottom side ofFIG. 70, a dashed box (a) of FIG. 70, illustrates signaling informationrelated to RB mapping according to DP types, which is transmittedthrough the PLS 35010, and the right bottom side of FIG. 70, a dashedbox (b) of FIG. 70, illustrates signaling information related to RBmapping according to DP types, which is transmitted through in-bandsignaling 35020. In-band signaling 35020 is processed, e.g., coded,modulated, and time-interleaver, together with data included in thecorresponding DP, and thus may be indicated as being included as partsof data symbols in the signal frame. Each type of signaling informationhas been described above and thus is not described here.

As illustrated in FIG. 70, the broadcast signal reception apparatus mayacquire the signaling information related to RB mapping according to DPtypes, which is included in the PLS 35010, and thus may demap andacquire DPs mapped to the corresponding signal frame 35000. Further, thebroadcast signal reception apparatus may acquire the signalinginformation related to RB mapping according to DP types, which istransmitted through in-band signaling 35020, and thus may demap DPsmapped to the next signal frame 35100.

FIG. 71 is a view illustrating signal frame structures according toanother embodiment of the present invention.

Each of signal frames 41010 and 41020 illustrated m the upper side ofFIG. 71 may include a preamble P, head/tail edge symbols EH/ET, one ormore PLS symbols PLS and a plurality of data symbols (marked as “DATAFrame N” and “DATA Frame N+1”). This is variable according to theintention of a designer. “T_Sync” marked in each signal frame of FIG. 71refers to a time necessary to achieve stable synchronization for PLSdecoding based on information acquired from a preamble by a receiver. Adescription is now given of a method for allocating a PLS offset portionby the frame structure module to ensure T_Sync time.

The preamble is located at the very front of each signal frame and maytransmit a basic transmission parameter for identifying a broadcastsystem and the type of signal frame, information for synchronization,information about modulation and coding of a signal

included in the frame, etc. The basic transmission parameter may includeFFT size, guard interval information, pilot pattern information, etc.The information for synchronization may include carrier and phase,symbol timing and frame information. Accordingly, a broadcast signalreception apparatus according to another embodiment of the presentinvention may initially detect the preamble of the signal frame,identify the broadcast system and the frame type, and selectivelyreceive and decode a broadcast signal corresponding to a receiver type.

Further, the receiver may acquire system information using informationof the detected and decoded preamble, and may acquire information forPLS decoding by additionally performing a synchronization procedure. Thereceiver may perform PLS decoding based on the information acquired bydecoding the preamble.

To perform the above-described function of the preamble, the preamblemay be transmitted with a robustness several dB higher than that ofservice data. Further, the preamble should be detected and decoded priorto the synchronization procedure.

The upper side of FIG. 71 illustrates the structure of signal frames inwhich PLS symbols are mapped subsequently to the preamble symbol or theedge symbol EH. Since the receiver completes synchronization after atime corresponding to T_Sync, the receiver may not decode the PLSsymbols immediately after the PLS symbols are received. In this ease, atime for receiving one or more signal frames may be delays until thereceiver decodes the received PLS data. Although a buffer may be usedfor a case in which synchronization is not completed before PLS symbolsof a signal frame are received, a problem in which a plurality ofbuffers are necessary may be caused.

Each of signal frames 41030 and 41040 illustrated in the bottom of FIG.71 may also include the symbols P, EH, ET, PLS and DATA Frame Nillustrated in the upper side of FIG. 71.

The frame structure module according to another embodiment of thepresent invention may configure a PLS offset portion 41031 or 41042between the head edge symbol EH and the PLS symbols PLS of the signalframe 41030 or 41040 for rapid service acquisition and data decoding. Ifthe frame structure module configures the PLS offset portion 41031 or41042 in the signal frame, the preamble may include PLS offsetinformation PLS_offset. According to an embodiment of the presentinvention, the value of PLS_offset may be defined as the length of OFDMsymbols used to configure the PLS offset portion.

Due to the PLS offset portion configured in the signal frame, thereceiver may ensure T_Sync corresponding to a time for detecting anddecoding the preamble.

A description is now given of a method for determining the value of PLSoffset.

The length of an OFDM symbol in the signal frame is defined as T_Symbol.If the signal frame does not include the edge symbol EH, the length ofOFDM symbols including the PLS offset (the value of PLS_offset) may bedetermined as a value equal to or greater than a celling value (orrounded-up value) of T_Sync/T_Symbol.

If the signal frame includes the edge symbol EH, the length of OFDMsymbols including PLS_offset may be determined as a value equal to orgreater than (a celling value (or rounded-up value) ofT_Sync/T_Symbol)-1.

Accordingly, the receiver may know of the structure of the receivedsignal frame based on data including the value of PLS_offset which isacquired by detecting and decoding the preamble. If the value ofPLS_offset is 0, it can be noted that the signal frame according to anembodiment of the present invention has a structure in which the PLSsymbols are sequentially mapped subsequently to the preamble symbol.Alternatively, if the value of PES offset is 0 and the signal frameincludes the edge symbol, the receiver may know of the signal frame hasa structure in which the edge symbol and the PLS symbols aresequentially mapped subsequently to the preamble symbol.

The frame structure module may configure the PLS offset portion 41031 tobe mapped to the data symbols DATA Frame N or the PLS symbols PLS.Accordingly, as illustrated in the bottom of FIG. 71, the framestructure module may allocate data symbols to which data of a previousframe (e.g., Frame N-1) is mapped, to the PLS offset portion.Alternatively, although not shown in the bottom of FIG. 71, the framestructure module may allocate PLS symbols to which PLS data of a nextframe is mapped, to the PLS offset portion.

The frame structure module may perform one or more quantizationoperations on PLS_offset to reduce signaling bits of the preamble.

A description is now given of an example in which the frame structuremodule allocates 2 bits of PLS_offset to the preamble to be signaled.

If the value of PLS_offset is “00”, the length of the PLS offset portionis 0. This means that the PLS data is mapped in the signal frameimmediately next to the preamble or immediately next to the edge symbolif the edge symbol is present.

If the value of PLS_offset is “01”, the length of the PLS offset portionis 1/4*L_Frame. Here, L_Frame refers to the number of OFDM symbols whichcan be included in a frame.

If the value of PLS_offset is “10”, the length of the PLS offset portionis 2/4*L_Frame.

If the value of PLS offset is “11”, the length of the PLS offset portionis 3/4*L_Frame,

The above-described method for determining the value of PLS_offset andthe length of the PLS offset portion by the frame structure module ismerely an exemplary embodiment, and terms and values thereof may varyaccording to the intention of a designer.

As described above, FIG. 71 illustrates a frame structure in a ease whena time corresponding to a plurality of OFDM symbols (PLS offset) istaken for synchronization after the preamble is detected and decoded.After the preamble is detected and decoded, the receiver may compensateinteger frequency offset, fractional frequency offset and samplingfrequency offset for a time for receiving a plurality of OFDM symbols(PLS_offset) based on information such as a continual pilot and a guardinterval.

A description is now given of an effect achievable when the framestructure module according to an embodiment of the present inventionensures T_Sync by allocating the PLS offset portion to the signal frame.

If the signal frame includes the PLS offset portion, a reception channelscanning time and a service data acquisition time taken by the receivermay be reduced.

Specifically, PLS information in the same frame as the preamble detectedand decoded by the receiver may be decoded within a time for receivingthe frame, and thus the channel scanning time may be reduced. In futurebroadcast systems, various systems can transmit data in a physical frameusing TDM and thus the complexity of channel scanning is increased. Assuch, if the structure of the signal frame to which the PLS offsetportion is allocated according to an embodiment of the present inventionis used, the channel scanning time may be reduced more.

Further, compared to the structure of the signal frame to which the PLSoffset portion is not allocated (in the upper side of FIG. 71), in thestructure of the signal frame to which the PLS offset portion isallocated (in the bottom of FIG. 71), the receiver may expect a servicedata acquisition time gain corresponding to the difference between thelength of the signal frame and the length of the PLS_offset portion.

The above-described effect of allocating the PLS offset portion may beachieved in a case when the receiver cannot decode PLS data in the sameframe as the received preamble symbol. If the frame structure module canbe designed to decode the preamble and the edge symbol withoutallocating the PLS offset portion, the value of PLS_offset may be set to0.

FIG. 72 is a diagram showing a frame structure according to anembodiment of the present invention.

This figure is partially the same as the frame structure described abovein relation to FIG. 10, and concepts of the two frame structure are thesame. FIG. 72 shows an example configuration of the frame types and FRUsin a super-frame. The top and middle parts of FIG. 72 show a super-frameand FRUs included In the super-frame, respectively. The bottom part ofFIG. 72 shows the number of frames included in each FRU (this number isup to 4 according to an embodiment of the present invention and isvariable depending on intension of a designer) and profiles (base,handheld and advanced) transmitted in the frames and a FEF. As describedabove, the frames according to an embodiment of the present inventioncan transmit 3 types of profiles. Unlike FIG. 10(c), FIG. 72 shows anexample in which the frames according to an embodiment of the presentinvention can transmit an advanced profile.

A super-frame may be composed of eight FRUs. The FRU is a basicmultiplexing unit for TDM(Time division multiplexing) of the frames, andis repeated eight times in a super-frame.

The TDM scheme can easily change transmission parameters (FFT, pilotpattern, etc.) per frame compared to frequency division multiplexing(FDM) scheme, and thus may be advantageous to simultaneously transmitdifferent PHY profiles. In addition, a low-power mobile receiver may bedesigned using the TDM scheme.

Each frame in the FRU belongs to one of the PHY profiles, (base,handheld, advanced) or FEF. The maximum allowed number of the frames inthe FRU is four and a given PHY profile can appear any number of timesfrom zero times to four times in the FRU (e.g., base, base, handheld,advanced). PHY profile definitions can be extended using reserved valuesof the PHY_PROFILE in the preamble, if required.

The FEF part is inserted at the end of the FRU, if included. When theFEF is included in the FRU, the minimum number of FEFs is 8 in asuper-frame. It is not recommended that FEF parts be adjacent to eachother.

The above-described FRU structure according to an embodiment of thepresent invention may have flexibility and may minimize signalingoverhead for signaling a super-frame structure. The number of framesincluded in each FRU and the number of FRUs included in a super-frameare variable depending on intention of a designer. In addition, asuper-frame according to the present invention is a concept includingframes within a specific time period and the term itself is variabledepending on intension of a designer.

FIG. 73 is a diagram showing the structure of OFDM symbols included inone frame.

Specifically, FIG. 73 is a diagram showing the structure of OFDM symbolsin a case when a frame transmits a base profile. Although this figureshows a frame for transmitting a base profile, frames for transmitting ahandheld profile and an advanced profile may also have the same OFDMsymbol structure.

One frame is further divided into a number of OFDM symbols and apreamble. As shown in FIG. 73, the frame comprises a preamble, one ormore frame signaling symbols (FSS), normal data symbols and a frame edgesymbol (FES). Descriptions of symbols in this figure may be the same asthose given above in relation to FIG. 10.

The preamble is a special symbol that enables fast Futurecast UTB systemsignal detection and provides a set of basic transmission parameters forefficient transmission and reception of the signal. Preamble signalingdata carries 21 bits of information that are needed to enable thereceiver to access PLS data and trace DPs within the frame structure.Signaling data may be included. A description of the preamble signalingdata included in the preamble is the same as that given above inrelation to FIG. 12.

The main purpose of the FSS(s) is to carry the PLS data. For fastsynchronization and channel estimation, and hence fast decoding of PLSdata, the FSS has more dense pi lot pattern than the normal data symbol.The FES has exactly the same pilots as the FSS, which enablesfrequency-only Interpolation within the FES and temporal interpolation,without extrapolation, for symbols immediately preceding the FES.

FIG. 74 is a table showing Signaling format for FRU configuration.

Future broadcast services can simultaneously transmit different PHYprofiles or a FEF per FRU, per super-frame, or per channel. A channelscan time can increase as different PHY profiles are simultaneouslytransmitted. Accordingly, to prevent the channel scan time fromincreasing, information about arrangement of the PHY profiles or the FEFin FRU needs to be signaled.

The broadcast signal transmitter according to an embodiment of thepresent invention may perform FRU configuration signaling in two stepsas described below. First, a preamble signals whether PHY profiles and aFEF are present in a super-frame or a FRU. That is, a preamble accordingto an embodiment of the present invention may signal includedPHY_PROFILE and FRU_CONFIGURE.

Second, a PLS signals the order and accurate length information of thePHY profiles or the FEF. That is, signaling fields such asFRU_PHY_PROFILE, FRU_FRAME_LENGTH and FRU_GI_FRACTION included in PLS1may indicate the order and the accurate length information of the PHYprofiles or the FEF. Descriptions of FRU_PHY_PROFILE, FRU_FRAME_LENGTHand FRU_GI_FRACTION are the same as those given above in relation toFIG. 13.

By signaling FRU configuration in two steps as described above, thereceiver may acquire information about whether desired PHY profiles or aFEF are present in a corresponding channel(or super-frame or FRU), bydecoding only the preamble. That is, an exit condition for allowing thereceiver to scan a desired channel (or super-frame or FRU) fast may beprovided by signaling the FRU configuration information in the preamble.

In addition, the FRU configuration signal according to an embodiment ofthe present invention is included in the preamble and PLS1. Accordingly,the receiver may acquire location information of PHY profiles or a FEFtransmitted in a certain time period (e.g., a super-frame period in thepresent invention) by accessing any frame within the time period. Thisenables efficient power consumption in a case when the receiver performschannel scan and channel switch.

The table of FIG. 74 is the same as Table 8 above. A description is nowgiven of the table of Signaling format for FRU configuration. Aspreviously described, configuration of a frame present in a channel maybe recognized through FRU _CONFIGURE. Herein, the range which can beindicated by FRU_CONFIGURE may be the whole channel or a superframe. Asdescribed above, if a superframe is constructed by repetition of a framerepetition unit (FRU), the FRUs having the same configuration may berepeated in a superframe, and therefore frame configuration of the FRUmay also be recognized through FRU_CONFIGURE.

As described above, PHY_PROFILE informs of the type of a frame havingthe preamble. That is, if PHY_PROFILE is set to 000, the frame may be aframe according to a base profile. If it is set to 001, the frame may bea frame according to a hand-held profile. If PHY_PROFILE is set to 010,the frame may be a frame according to an advanced profile. IfPHY_PROFILE is set to 111, the frame may be a future extension frame(FEF), namely, a frame for another system to be used In the future.

According to one embodiment, the FRU_CONFIGURE field may have 3 bits.Each bit may indicate whether or not a frame according to a specificprofile is present In the superframe.

To represent all configurations of a superframe with a small number ofbits, the FRU_CONFIGURE field indicates whether or not a frame accordingto a specific profile is present in the superframe in relation to thetype of a current frame. That is, configurations of the superframe maybe distinguished by combinations of FRU_CONFIGURE and PHY_profile.

If FRU_CONFIGURE is set to 000, the channel or the superframe mayconsist of frames of one type which are not mixed with other types offrames. That is, if the profile of the current frame is a base profile(PHY_PROFILE=000), and the value of FRU_CONFIGURE is 000, only framesaccording to the base profile may be present in the superframe.

in the case in which the profile of the current frame is a base profile(PHY_PROFILE=000), if the first bit of FRU_CONFIGURE is set to 1, aframe according to the handheld profile may be present in thesuperframe. If the second bit of FRU_CONFIGURE is 1, a frame accordingto the advanced profile may be present in the superframe. If the thirdbit of FRU_CONFIGURE is 1, an FEF may be present in the superframe.

If the profile of the current frame is not the base profile, meaning ofeach bit of FRU_CONFIGURE may change. For example, in the case in whichthe profile of the current frame is the handheld profile(PHY_PROFILE=001), if the first bit of FRU_CONFIGURE is 1, a frameaccording to the base profile may be present in the superframe. If thesecond bit of FRU_CONFIGURE is 1, a frame according to the advancedprofile may be present in the superframe. If the third bit ofFRU_CONFIGURE is 1, an FEF may be present in the superframe.

For example, if the profile of the current frame is the advanced profile(PHY_PROFILE=010), and the value of FRU_CONFIGURE is 011, a frameaccording to the base profile is not present in the superframe, whereasa frame according to the handheld profile and an FEF are present in thesuperframe.

In this manner, all possible configurations that the superframe can havemay be represented. With the present invention, a large number ofsuperframe configurations may be represented with a smaller number ofbits through combination with the “current frame type indicating field;”(PHY_PROFILE). That is, the present invention implements efficientsignaling for a preamble with a limited number of bits, and providesminimum information allowing the receiver to implement fast channelscanning.

FIG. 75 is a diagram showing preamble signaling of FRU configurationaccording to an embodiment of the present invention.

FIG. 75 shows a FRU consisting of 4 frames. The frames included in theFRU according to the current embodiment include a base profile, ahandheld profile, an advanced profile and a FEF_PHY_PROFILE andFRU_CONFIGURE values are written under each frame. The PHY_PROFILE andFRU_CONFIGURE values described below are based on the table of FIG. 74.These values are variable depending on intension of a designer.

Initially, the first frame transmits the base profile and thus has aPHY_PROFILE value of ‘000’.

The second frame transmits the handheld profile and thus has aPHY_PROFILE value of ‘001’.

The third frame transmits the advanced profile and thus has aPHY_PROFILE value of ‘010’.

The fourth frame transmits the FEF and thus has a PHY_PROFILE value of‘111’.

FRU_CONFIGURE may be determined for each frame per FRU.

Initially, FRU_CONFIGURE, may be determined based on the first frame. Inthe case of the first frame, since a current frame is the base profile,FRU_CONFIGURE may be determined based on the first and second columns ofthe table of FIG. 74. If the handheld profile is present In the FRU,FRU_CONFIGURE is ‘1XX’. If the advanced profile is present in the FRU,FRU_CONFIGURE is ‘X1X’. If the FEF is present in the FRU, FRU_CONFIGUREis ‘XX1’. Accordingly, FRU_CONFIGURE determined based on the first frameof this figure is ‘111’.

Likewise, FRU_CONFIGURE may be determined based on the second frame. Inthe case of the second frame, since a current frame is the handheldprofile, FRU_CONFIGURE may be determined based on the first and thirdcolumns of the table of FIG. 74. If the base profile is present in theFRU, FRU_CONFIGURE is ‘1XX’. If the advanced profile is present in theFRU, FRU_CONFIGURE is ‘X1X’. If the FEF is present in the FRU,FRU_CONFIGURE is ‘XX1’. Accordingly, FRU_CONFIGURE determined based onthe second frame of this figure is ‘111’.

Similarly, FRU_CONFIGURE may be determined based on the third frame. Inthe case of the third frame, since a current frame is the advancedprofile, FRU_CONFIGURE may be determined based on the first and fourthcolumns of the table of FIG. 74. Accordingly, FRU_CONFIGURE determinedbased on the third frame of this figure is ‘111’. In the same manner,FRU_CONFIGURE may be determined based on the fourth frame. In the caseof the fourth frame, since a current frame is the FEF, FRU_CONFIGURE maybe determined based on the first and fifth columns of the table of FIG.74. Accordingly, FRU_CONFIGURE determined based on the fourth frame ofthis figure is ‘111’.

FIG. 76 is a diagram showing PLS signaling of FRU configurationaccording to an embodiment of the present invention.

As described above, the broadcast signal transmitter according to anembodiment of the present invention may signal corresponding informationin each of FRU_PHY_PROFILE, FRU_FRAME_LENGTH and FRU_GI_FRACTION fieldsof a PLS.

FIG. 76 shows a FRU consisting of 4 frames. The frames included in theFRU according to the current embodiment include a base profile, ahandheld profile, an advanced profile and a FEF, NUM_FRAME_FRU, andFRU_PHY_PROFILE, FRU_FRAME_LENGTH and FRU_GI_FRACTION field values ofeach frame are written under the frames. A description is now given ofeach parameter.

NUM_FRAME_FRU field indicates the number of the frames per FRU.Accordingly, NUM_FRAME_FRU=“00” may represent a case in which the FRUincludes one frame, NUM_FRAME_FRU=“01” may represent a case in which theFRU includes two frames, NUM_FRAME_FRU=“10” may represent a case inwhich the FRU includes three frames, and NUM_FRAME_FRU=“11” mayrepresent a case in which the FRU includes four frames.

The value of i may be determined depending on the NUM_FRAME_FRU value.According to an embodiment of the present invention, sinceNUM_FRAME_FRU=“11”, i can have values from 0 to 3.

The first frame included in the FRU of this figure transmits the baseprofile and thus FRU_PHY_PROFILE = “000”, the second frame transmits thehandheld profile and thus FRU_PHY_PROFILE=“001”, the third frametransmits the advanced profile and thus FRU_PHY_PROFILE=“010”, and thefourth frame transmits the FEF and thus FRU_PHY_PROFILE=“111”.

FRU _FRAME_LENGTH represents the length of each frame. According to anembodiment of the present invention, the length of the frame isincreased by 50 ms as the FRU_FRAME_LENGTH value is increased by 1.Accordingly, for example, FRU_FRAME_LENGTH=“00” if the frame length is50 ms, FRU_FRAME_LENGTH=“01” if the frame length is 100 ms,FRU_FRAME_LENGTH=“10” if the frame length is 150 ms, andFRU_FRAME_LENGTH=“11” if the frame length is 200 ms.

FRU_GI_FRACTION represents a guard interval fraction value of eachframe. According to an embodiment of the present invention, for example,the FRU_GI_FRACTION value may be based on Table 7.

This figure shows an example in which the guard interval fraction valueis 1/80 if FRU_GI_FRACTION=“100”, and the guard interval fraction valueis 1/20 if FRU_GI_FRACTION=“001”.

Overhead of the PLS to be transmitted may be reduced or increaseddepending on the NUM_FRAME_FRU value transmitted through the PLS.Accordingly, as the NUM_FRAME_FRU value is reduced, overhead of the PLSmay be reduced. If the length of the PLS is variable, the preamble mayinclude information corresponding to the length of the PLS.

The preamble may transmit minimum essential information for efficiencyand robustness. If the length of the PLS is fixed, the preamble may nottransmit information corresponding to the length of the PLS.Accordingly, compared to the case in which the length of the PLS isvariable, if the length of the PLS is fixed, the preamble mayefficiently and robustly transmit signaling information.

The case in which the length of the PLS is fixed may refer to a case inwhich a fixed length is assigned to the PLS.

If the length of the PLS is fixed, the broadcast signal receiveraccording to an embodiment of the present invention may perform zeropadding by the difference between the NUM_FRAME_FRU value and theassigned PLS length.

The above description corresponds to an embodiment of the presentinvention, and names, functions, values, etc. of the signaling fieldsare variable depending on intension of a designer.

FIG. 77 is a diagram showing syntax of the PLS signaling field describedabove in relation to FIG. 76.

The broadcast signal receiver according to an embodiment of the presentinvention may allocate 2 bits, 3 bits, 2 bits and 3 bits to theNUM_FRAME_FRU, FRU_PHY_PROFILE, FRU_FRAME_LENGTH and FRU_GI_FRACTIONsignaling fields, respectively. Descriptions of the signaling fields ofFIG. 47 are the same as those given above in relation to FIGS. 13 and76.

The number of for loops is determined based on the NUM_FRAME_FRU value.FIG. 77 shows an example in which the NUM_FRAME_FRU value is “11” and iis from 0 to 3. Accordingly, the number of for loops is determined as 4.The for loop may be a unit for distinguishing individual signalinginformation of each frame included in a FRU.

The number, of for loops may be changed based on whether the length ofthe PLS is fixed, as described above in relation to FIG. 76. That is, ifthe length of the PLS is variable, the number of for loops may bedetermined based on the NUM_FRAME_FRU value. On the other hand, if thelength of the PLS is fixed, the number of for loops may also be fixed.For example, the number of for loops may be fixed to 4.

The broadcast signal transmitter according to an embodiment of thepresent invention may include FRU_PHY_PROFlLE, FRU_FRAME_LENGTH andFRU_GI_FRACTION information corresponding to the number of for loops.

As described above in relation to FIG. 13, using FRU_FRAME_LENGTHtogether with FRU_GI_FRACTION, the exact value of the frame duration canbe obtained.

FIG. 78 is a table showing Number of OFDM symbols per frame for each FFTand frame length according to an embodiment of the present invention.

The frame length is divided into four, i.e., 50, 100, 150 and 200 ms,and FRU_FRAME_LENGTH is signaled using 2 bits in FIG. 76 to minimizesignaling overhead.

Specifically, FIG. 78 is a table showing Number of OFDM symbols perframe for each FFT and frame length in a case when FRU_FRAME_LENGTH 1 issignaled using 2 bits as in FIG. 76. As described above in relation toFIGS. 13, 76 and 77, using FRU_FRAME_LENGTH together withFRU_GI_FRACTION, the exact value of the frame duration can be obtained.

The table of FIG. 78 shows the number of OFDM symbols included in oneframe depending on FRU_FRAME_LENGTH when FFT sizes are 32K, 16K and 8K.For example, when the FFT size is 32K, if FRU_FRAME_LENGTH is “00”, 9OFM symbols may be included in one frame. Likewise, when the FFT size is32K, 18 OFM symbols may be included in one frame if FRU_FRAME_LENGTH is“01”, 27 OFM symbols may be included in one frame If FRU_FRAME_LENGTH is“10”, and 36 OFM symbols may be included in one frame ifFRU_FRAME_LENGTH is “11”.

When the FFT size is 16K, If FRU_FRAME_LENGTH is “00”, 18 OFM symbolsmay be included in one frame. Likewise, when the FFT size is 16K, 36 OFMsymbols may be included in one frame if FRU_FRAME_LENGTH is “01”, 54 OFMsymbols may be included in one frame if FRU_FRAME_LENGTH is “10”, and 72OFM symbols may be included in one frame if FRU_FRAME_LENGTH is “11”.

When the FFT size is 8K, if FRU_FRAME_LENGTH is “00”, 36 OFM symbols maybe included in one frame. Likewise, when the FFT size is 8K, 72 OFMsymbols may be included in one frame if FRU_FRAME_LENGTH is “01”, 108OFM symbols may be included in one frame if FRU_FRAME_LENGTH is “10”,and 144 OFM symbols may be included in one frame if FRU_FRAME_LENGTH is“11”.

The broadcast signal transmitter according to an embodiment of thepresent invention may determine the number of OFDM symbols included inone frame based on FRU_FRAME_LENGTH and FFT size.

The table shown in FIG. 78 merely corresponds to an embodiment and isvariable depending on intension of a designer.

The broadcast signal transmitter according to an embodiment of thepresent invention may extend bits of FRU_FRAME_LENGTH. Specifically, thebroadcast signal transmitter according to an embodiment of the presentinvention may extend bits of FRU_FRAME_LENGTH if service having a lowdata rate other than video service is provided or if service having anarbitrary frame length is provided using a FEF region.

For example, if the broadcast signal transmitter according to anembodiment of the present invention controls the frame length per OFDMsymbol, when the FFT size is 8K, up to 144 OFDM symbols should besignaled and thus 8 bits may be allocated to FRU_FRAME_LENGTH.

Alternatively, the broadcast signal transmitter according to anembodiment of the present invention may control the frame length basedon 32K FFT to adjust signaling overhead and flexibility. In this ease,the broadcast signal transmitter according to an embodiment of thepresent invention should signal up to 36 OFDM symbols and thus mayextend the bits of FRU_FRAME_LENGTH to 6 bits.

A description of a method for signaling FRU_FRAME_LENTH using 6 bits bythe broadcast signal transmitter according to an embodiment of thepresent invention will be given below with reference to FIG. 80.

FIG. 79 is a table showing frame length in millisecond per frame foreach FFT and GI fraction according to an embodiment of the presentinvention.

Specifically, FIG. 79 is a table showing frame length in millisecond perframe for each FFT and GI fraction in a case when FRU_FRAME_LENTH issignaled using 6 bits.

In the table, GIF denotes a guard interval fraction and N_Sym denotesthe number of OFDM symbols per frame.

When FRU_FRAME_LENTH is signaled using 6 bits, up to 64 OFDM symbols maybe included in one frame. In addition, the broadcast signal transmitteraccording to an embodiment of the present invention may support frameshaving frame lengths up to 300 ms or above as shown in the table of FIG.79.

However, if the maximum frame length is limited to 250 ms due to channelscan or the like (e.g., DTB-T2 broadcast standard), the maximum numberof OFDM symbols using 6 bits and not exceeding 250 ms may be saturatedand used. Accordingly, shaded parts in the table of FIG. 79 may not bevalid. In this case, the number of OFDM symbols may be limited to 44 to50 depending on the FFT size and the GI fraction value.

FIG. 80 is a table showing Number of OFDM symbols per frame for each FFTand frame length according to an embodiment of the present invention.

Specifically, FIG. 80 is a table showing another embodiment of Number ofOFDM symbols per frame for each FFT and frame length in a case whenFRU_FRAME_LENTH is signaled using 2 bits in FIG. 78. That is, FIG. 80 isa table showing Number of OFDM symbols per frame for each FFT and framelength in a case when FRU_FRAME LENTH is signaled using 6 bits.

The broadcast signal transmitter according to an embodiment of thepresent invention may determine the number of OFDM symbols included inone frame depending on FFT size and FRU_FRAME_LENGTH based on the tableof FIG. 80. For example, when the FFT size is 32K, if FRU_FRAME_LENGTHis “000000”, 1 OFDM symbol may be included in one frame. Likewise, whenthe FFT size is 32K, 2 OFDM symbols may be included in one frame ifFRU_FRAME_LENGTH is “000001”, 3 OFDM symbols may be included in oneframe if FRU_FRAME_LENGTH is “000010”, and 35 OFDM symbols may beincluded in one frame if FRU_FRAME_LENGTH is “100010”.

In the same manner, the broadcast signal transmitter according to anembodiment of the present invention may determine the number of OFDMsymbols included in one frame in a case when the FFT sizes are 16K and8K. depending on the FRU_FRAME_LENGTH value based on the fable of FIG.80.

FIG. 80 shows an example in which the maximum number of OFDM symbolsincluded in one frame is limited to 36, 72 and 144 depending on FFTsizes. This corresponds to an example in which the frame length islimited to 200 ms. However, when the broadcast-signal transmitteraccording to an embodiment of the present invention desires to extendthe frame length to 250 ms, the broadcast signal transmitter may designthe maximum number of OFDM symbols with reference to FIG. 79 in such amanner that the frame length does not exceed 250 ms.

Numerical values indicated in FIGS. 78 to 80 are variable depending onintension of a designer.

FIG. 81 is a flowchart of a broadcast signal transmission methodaccording to an embodiment of the present invention.

The broadcast signal transmitter according to an embodiment of thepresent invention may encode data for transmitting at least onebroadcast service component (or service data) (S83000). As describedabove, the data according to an embodiment of the present invention maybe processed per DP corresponding to the data. The data may be encodedby the bit interleaved coding & modulation block 1010.

Then, the broadcast signal transmitter according to an embodiment of thepresent invention may build at least one signal frame (S83010). Thesignal frame according to an embodiment of the present invention mayinclude PLS data and service data. The signal frame may be built by theframe building block 1020.

After that, the broadcast signal transmitter according to an embodimentof the present invention may modulate the built at least one signalframe by an OFDM scheme (S83020). The signal frame may be OFDM-modulatedby the waveform generation module 1030.

Then, the broadcast signal transmitter according to an embodiment of thepresent invention may insert a preamble into the built at least onesignal frame. The preamble inserted into the signal frame may be anormal preamble, a robust preamble or an extended (or enhanced)preamble. The broadcast signal transmitter according to an embodiment ofthe present invention may insert a normal preamble, a robust preamble oran extended preamble into the signal frame depending on a channelenvironment for transmitting the signal frame. As described above, therobust preamble may be generated by repeating a normal preamble, in thiscase, the first half of the robust preamble is exactly the same as thenormal preamble, and the second half of the robust preamble is a simplevariation of the normal preamble where the difference arises from thesequence SSS applied in the frequency domain.

The extended preamble may have a form in which a plurality of normalpreambles are repeated. As described above in relation to FIG. 47, twoOFDM data regions included in the extended preamble according to anembodiment of the present invention, i.e., OFDM data A and OFDM data B,may transmit different signaling data. A description of the extendedpreamble may be the same as that given above in relation to FIGS. 47 to50.

The preamble insertion block 8050 according to an embodiment of thepresent invention may insert one of the above-described preambles intothe signal frame.

To generate the robust preamble, the preamble insertion block 8050according to an embodiment of the present invention may generate a firsthalf of the robust preamble and a second half of the robust preambleusing different scrambling sequences, or using the same scramblingsequence but different carrier allocation schemes. The first half andthe second half of the robust preamble generated according to anembodiment of the present invention may have different signal waveformsin the time domain. Accordingly, even when the same signalinginformation is repeatedly transmitted in the time domain, data offsetdue to a multipath channel does not occur.

To generate the extended preamble, the preamble insertion block 8050according to an embodiment of the present invention may generate a firsthalf of the robust preamble and a second half of the robust preambleusing different scrambling sequences, or using the same scramblingsequence but different carrier allocation schemes. A period in which thenormal preamble structure is repeated in the extended preamble generatedaccording to an embodiment of the present invention may have differentsignal waveforms in the time domain.

The signal frame according to an embodiment of the present invention mayinclude a preamble and PLS data. Total signaling fields included in thepreamble and the PLS data may be referred to as signaling data.Alternatively, only signaling fields included in the PLS data may bereferred to as signaling data.

As described above in relation to FIGS. 72 to 80, the signaling dataaccording to an embodiment of the present invention may include FRUconfiguration information or length information of each frame includedin a super frame. Specifically, the broadcast signal transmitteraccording to an embodiment of the present invention may signalinformation about whether PHY profiles and a FEF are present in asuper-frame or a FRU, i.e., PHY_PROFILE and FRU_CONFlGURE, as the FRUconfiguration signaling information.

In addition, the signaling data according to an embodiment of thepresent invention may include the order and accurate length informationof the PHY profiles or the FEF. That is, signaling fields such asFRU_PHY_PROFILE, FRU_FRAME_LENGTH and FRU_GI_FRACTION may indicate theorder and the accurate length information of the PHY profiles or theFEF. Descriptions of FRU_PHY_PROFILE, FRU_FRAME_LENGTH andFRU_GI_FRACTION are the same as those given above in relation to FIG.13.

Then, the broadcast signal transmitter according to an embodiment of thepresent invention may transmit at least one broadcast signal includingthe built and modulated at least one signal frame (S83030).

FIG. 82 is a flowchart of a broadcast signal reception method accordingto an embodiment of the present invention.

FIG. 82 corresponds to an inverse procedure to the broadcast signaltransmission method described above in relation to FIG. 81.

The broadcast signal receiver according to an embodiment of the presentinvention may receive at least one broadcast signal (S84000). Thebroadcast signal according to an embodiment of the present inventionincludes at least one signal frame, and each signal frame may include apreamble and PLS data, and service data.

A description of signaling data included in the preamble and the PLSdata is the same as that given above in relation to FIG. 81 and thus isomitted here.

The broadcast signal according to an embodiment of the present inventionmay include one or more signal frames. Each signal frame may include apreamble and edge, PLS and data symbols. As described above, thebroadcast signal receiver having received the broadcast signal maydetect the preamble and descramble the preamble based on a scramblingsequence applied when the broadcast signal transmitter generates thepreamble. In this case, the preamble may be a normal preamble or arobust preamble. Then, the broadcast signal receiver may acquire thesignaling data included in the preamble.

A preamble detector included in the synchronization & demodulation block9000 according to an embodiment of the present invention may detect anddescramble the preamble. That is, the preamble detector may performinverse operation to that of the preamble insertion block 7500. Asdescribed above, the preamble detector may perform different operationsdepending on the type of the preamble (a normal preamble, a robustpreamble or an extended preamble) included in the signal frame.

Specific descriptions of the operations may be the same as those givenabove in relation to FIGS. 43 to 46, and 48 to. 50.

The broadcast signal receiver according to an embodiment of the presentinvention may demodulate the received at least one broadcast signal byan OFDM scheme (S84010). The broadcast signal may be demodulated by thesynchronization & demodulation module 9000.

Then, the broadcast signal receiver according to an embodiment of thepresent invention may parse at least one signal frame from thedemodulated broadcast signal (S84020). The signal frame may be parsed bythe frame parsing module 9010.

After that, the broadcast signal receiver according to an embodiment ofthe present invention may decode the service data for transmitting atleast one broadcast service component (S84030). The data may be decodedby the demapping & decoding module 9020.

It will be appreciated by those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

Both apparatus and method inventions are mentioned in this specificationand descriptions of both of the apparatus and method inventions may becomplementarily applicable to each other.

1-24. (canceled)
 25. A method for receiving broadcast signals by anapparatus for receiving broadcast signals, the method comprising:receiving the broadcast signals carrying a robust preamble and data ofat least one signal frame, wherein the robust preamble is positioned ata beginning of the at least one signal frame and a duration of therobust preamble is extensible in Orthogonal Frequency Division Multiplex(OFDM) symbol periods; detecting the robust preamble; demodulating thedata of the at least one signal frame by an OFDM scheme; parsing the atleast one signal frame; decoding service data in the at least one signalframe, wherein each signal frame is assigned to a frame type accordingto a Fast Fourier Transform (FFT) size, a guard interval length and apilot pattern, and wherein when two adjacent signal frames havingdifferent frame types are multiplexed in the broadcast signals, apreceding signal frame further includes a tail edge symbol beingpositioned at an end of the preceding signal frame.
 26. The method ofclaim 25, wherein the duration of the robust preamble is extensible byincreasing a number of OFDM symbols in the robust preamble.
 27. Themethod of claim 25, wherein the robust preamble includes two OFDMsymbols, wherein each of the two OFDM symbols of the robust preambleincludes emergency alert information.
 28. An apparatus for receivingbroadcast signals, the apparatus comprising: an antenna to receive thebroadcast signals carrying a robust preamble and data of at least onesignal frame, wherein the robust preamble is positioned at a beginningof the at least one signal frame and a duration of the robust preambleis extensible in Orthogonal Frequency Division Multiplex (OFDM) symbolperiods; a robust preamble detector to detect the robust preamble; ademodulator to demodulate the data of the at least one signal frame byan OFDM scheme; a frame parser to parse the at least one signal frame; adecoder to decode service data in the at least one signal frame, whereineach signal frame is assigned to a frame type according to a FastFourier Transform (FFT) size, a guard interval length and a pilotpattern, and wherein when two adjacent signal frames having differentframe types are multiplexed in the broadcast signals, a preceding signalframe further includes a tail edge symbol being positioned at an end ofthe preceding signal frame.
 29. The apparatus of claim 28, wherein theduration of the robust preamble is extensible by increasing a number ofOFDM symbols in the robust preamble.
 30. The apparatus of claim 28,wherein the robust preamble includes two OFDM symbols, wherein each ofthe two OFDM symbols of the robust preamble includes emergency alertinformation.